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[Q] Galaxy Nexus radio/modem failure, baseband version : unknown

Hi,
I'm new to this forum.
I got a new Samsung Galaxy Nexus (unlocked GSM-i9250) mobile thruoug Google Store and got it to India.
I did an OTA upgrade from ICE Stock 4.0.4 to stock JB 4.1.1. My next upgrade to 4.1.2 failed, though detected by system failed.
So I used the phone for about 2 days and one day after charging, there was no radio service. WIFI works. Tried another SIM
and operator but in vain.
As all my efforts of factory reset, reboot etc failed, I thought of reflashing the latest images.
So I downloaded the latest images from Google site, unlocked the bootloader, followed different threads
and tried updating to 4.1.2. System now boots to 4.1.2 and WIFI works, but no GSM service still.
In the phone settings
Basebad version : unknown
Network : Unknown
IEMI : unknown
Service state : Out of service/Radio off (keeps toggling every 4-5 sec)
So I tried going back to 4.0.4 and system boots back to 4.0.4, but no GSM service
No idea what is happening. Two of us bought at the same time and got the same to India. For my friend, the OTA updates
to 4.1.1 and 4.1.2 went through fine.
I saw similar issues reported but not able to figure out how finally they solved it.
Any suggestions/help is appreciated.
Thanks in advance
Sanu

sanu.mathews said:
Hi,
I'm new to this forum.
I got a new Samsung Galaxy Nexus (unlocked GSM-i9250) mobile thruoug Google Store and got it to India.
I did an OTA upgrade from ICE Stock 4.0.4 to stock JB 4.1.1. My next upgrade to 4.1.2 failed, though detected by system failed.
So I used the phone for about 2 days and one day after charging, there was no radio service. WIFI works. Tried another SIM
and operator but in vain.
As all my efforts of factory reset, reboot etc failed, I thought of reflashing the latest images.
So I downloaded the latest images from Google site, unlocked the bootloader, followed different threads
and tried updating to 4.1.2. System now boots to 4.1.2 and WIFI works, but no GSM service still.
In the phone settings
Basebad version : unknown
Network : Unknown
IEMI : unknown
Service state : Out of service/Radio off (keeps toggling every 4-5 sec)
So I tried going back to 4.0.4 and system boots back to 4.0.4, but no GSM service
No idea what is happening. Two of us bought at the same time and got the same to India. For my friend, the OTA updates
to 4.1.1 and 4.1.2 went through fine.
I saw similar issues reported but not able to figure out how finally they solved it.
Any suggestions/help is appreciated.
Thanks in advance
Sanu
Click to expand...
Click to collapse
I had a similar experience with my previous Nexus S device. The phone would start up perfectly fine but it wouldn't catch reception. I think I flashed the wrong radio.img file (there are a lot of Nexus S variants).
I would try the following steps:
- Flash CWM recovery
- Flash a custom ROM (you can use "Mounts and Storage" in CWM recovery to gain temporary access to your internal storage - you will need to do this to copy your ROM file there)
- If you like it, just stick to the custom ROM.
If you insist on going back to the stock ROM, there are threads here that guide you to go back to stock completely. Even if you go back to a previous ICS ROM (specific to your phone), you should start receiving OTA updates normally.
Best of luck!

Thanks for the reply.
I'm almost sure the radio image is fine. I downloaded the images from
Google Nexus developers site for "takju" for Galaxy Nexus "maguro" matching with my phone.
I flashed matching ROM and radio images from Google site. Tried both ICS 4.0.4 & JB 4.1.2
I'll try custom ROMs if nothing works out. I'm going to try this first time, so need to chk the threads first. This is my first Andriod phone and already ran into trouble after just 2 days of use, that too without any manual flashing. Only OTA happened before the issue.
Could the h/w have gone bad ?
In fastboot mode, the radio version is displayed correctly, but not after phone is up and running.
If the h/w has become faulty, I still expect the "Baseband version" in "About Phone" to be correct.
Is this assumption correct ? If it is s/w issue, I'm relived and I can try some custom image. So I'm hoping its only a s/w glitch.
Thanks a lot

you flashed the wrong rom on your phone and corrupted its efs partition. If you have a backup (why should you if you didn't even know that it was that to fail your phone's radio..) you could proceed and restore it. If you don't it's a big mess and you might have to go to a repair service.
Anyway you could still try and flash the original ROM for your phone and see if it fixes the problem. If not there are tools on the web (search the forums) that could try and restore your partition even if you don't have a backup.
If you succeed in restoring your phone don't EVER forget to backup you /efs partition

Thanks.
I tried flashing as the phone radio just stopped working after I charged the phone one day morning.
Let me follow your suggestions. I didn't know about efs partition. may be its messed up
What is puzzling me is, how can the factory images from google be wrong.
clait said:
you flashed the wrong rom on your phone and corrupted its efs partition. If you have a backup (why should you if you didn't even know that it was that to fail your phone's radio..) you could proceed and restore it. If you don't it's a big mess and you might have to go to a repair service.
Anyway you could still try and flash the original ROM for your phone and see if it fixes the problem. If not there are tools on the web (search the forums) that could try and restore your partition even if you don't have a backup.
If you succeed in restoring your phone don't EVER forget to backup you /efs partition
Click to expand...
Click to collapse

sanu.mathews said:
Thanks.
I tried flashing as the phone radio just stopped working after I charged the phone one day morning.
Let me follow your suggestions. I didn't know about efs partition. may be its messed up
What is puzzling me is, how can the factory images from google be wrong.
Click to expand...
Click to collapse
It's not the factory images to be wrong but the fact that if the /efs partition is really corrupted the stock images don't contain the info necessary to flash that partition as well.
In fact it may become corrupted after a wrong flashing but a new, correct, flash won't restore it. The only way back is the /efs backup.
What if you type *#06#? Does it show you an IMEI number or what?

*#06# shows "OK"
clait said:
It's not the factory images to be wrong but the fact that if the /efs partition is really corrupted the stock images don't contain the info necessary to flash that partition as well.
In fact it may become corrupted after a wrong flashing but a new, correct, flash won't restore it. The only way back is the /efs backup.
What if you type *#06#? Does it show you an IMEI number or what?
Click to expand...
Click to collapse

sanu.mathews said:
*#06# shows "OK"
Click to expand...
Click to collapse
Between the blue line and the OK it should show the sixteen digit long IMEI number. the fact that it isn't shown simplifies the diagnosis. I'm 100% sure you've got your /efs partition corrupted.
Please do a forum search on how to restore it.
Sent from my GT-I9300 using Tapatalk 2

Thanks a lot.
This eliminates so much un-wanted time waste/means no need to try various steps.
Can I get efs dump from another Galaxy nexus and flash it on mine after rooting ?
I'm under the impression that IEMI number etc should be in OTP and that can't get corrupted but efs may have some meta data regarding the same
clait said:
Between the blue line and the OK it should show the sixteen digit long IMEI number. the fact that it isn't shown simplifies the diagnosis. I'm 100% sure you've got your /efs partition corrupted.
Please do a forum search on how to restore it.
Sent from my GT-I9300 using Tapatalk 2
Click to expand...
Click to collapse

sanu.mathews said:
Can I get efs dump from another Galaxy nexus and flash it on mine after rooting ?
Click to expand...
Click to collapse
No can do, the IMEI is a per device unique number.
Check this thread and do some forum search: http://forum.xda-developers.com/showthread.php?t=1689525
You're not the only one that lost the IMEI so chances are likely to you to resolve your issue!

If I copy the IMEI number from the box or my working phone, will it work ?
What I want to know is, is it only coming from EFS or if IMEI is changed will be there be some signature that will fail etc
I have used fastboot but not sure about rooting, so need to read that before trying Rooting
In India, Samsung won't repair my phone as I got it from US.
Another worry is, let IMEI number be wrong and let there be no network, but atleast "Baseband version : Unknown" shdn't come in the phone, correct ? Coud there be any issue with radio image partition itself ?
clait said:
No can do, the IMEI is a per device unique number.
Check this thread and do some forum search: http://forum.xda-developers.com/showthread.php?t=1689525
You're not the only one that lost the IMEI so chances are likely to you to resolve your issue!
Click to expand...
Click to collapse

sanu.mathews said:
If I copy the IMEI number from the box or my working phone, will it work ?
What I want to know is, is it only coming from EFS or if IMEI is changed will be there be some signature that will fail etc
I have used fastboot but not sure about rooting, so need to read that before trying Rooting
In India, Samsung won't repair my phone as I got it from US.
Another worry is, let IMEI number be wrong and let there be no network, but atleast "Baseband version : Unknown" shdn't come in the phone, correct ? Coud there be any issue with radio image partition itself ?
Click to expand...
Click to collapse
Mate - I too am from India, and I too got the exact same problem, and I too tried all you did - all this about a month back. I have reconciled myself to the fact that its a hardware issue. Since samsung centers in India won't do any repairs, I'm afraid we're both stuck with really expensive music players.
My sympathies.

Fixed by sending in for warranty
Just an update...I was having all of these symptoms...unknown IMEI, Baseband, etc...basically gave me an expensive media player for a few months while waiting for a fix on XDA. After no update I decided to call up Samsung and after talking to 3 different technicians, I was able to send it in. Just a note for anyone about to do the same, they will try very hard to blame it on the carrier/SIM card, so save yourself some trouble and just say you already went to the physical store of your carrier (calling isn't enough)and they couldn't get it working. Once you get past that, they will email you a printable 2-day UPS shipping label so you can ship it to them for free. It took 2 weeks from the time I called to having a working phone back in my hands.
This was their fix:
Problem found:
NO PCS SERVICE
Solution:
REPLACED PBA
After a quick search I found that the PBA is the motherboard, so it's definitely a hardware issue. Hope you guys are still under warranty because I've heard this is ~$200 to fix otherwise.
Good luck.

[SOLVED] i317M - not connecting to network

Hello,
I started with Galaxy Note 2- i317M (rogers, canada), rooted with DN3 V4 beta installed. But I wanted to try DN4, so I created a back-up using TWRP and tried installing DN4. However, I later realized that it is not for the LTE versions yet and phone did not recognize SIM anymore. So I wiped the data and tried installing dn3 v5.5, but the phone still did not connect.
Losing all hope I installed DNv4 again, but it still did not work. So i finally just tried restoring from the back-up I made using TWRP. Everything in the phone is same except no network.
Finally I tried restoring from back-up after doing a complete wipe of internal storage and everything except the external card. But still the error does not go away. I researched more about the error and the fact that my imei shows up as null/null. I used the instructions of using EFS professional, but it did not work. The model number in my phone now shows up as SM-G900F and baseband shows as unknown, and it shows DN3V5 Rom despite the clean-up and restoring from DN3V4.
Any guidance available on this please...I need specific steps because after 12 hour search and try-outs I am lost now.....
UPDATE:
Solved it! Here is the solution for anyone in this problem
http://forum.xda-developers.com/showpost.php?p=46231268&postcount=4
worked like a charm.. No reason to throw this and get a new phone

I have had this problem. It didn't happen whilst flashing though. My imei number is now a generic one and I had no efs backup. After 5 days of trying everything I can find I'm giving up. My note 2 is dead as far as I'm concerned. As far as I'm aware to get my imei back I'll have to send it for repair so I'll buy another phone and not a Samsung

I don`t think your phones are dead. I didn`t try it personally, but I`m sure you can restore your EFS back. Just you need to do some research, maybe you could start here:
https://www.google.ro/?gws_rd=ssl#safe=off&q=how+to+recover+efs+folder
Do not give up, read on end you will eventually do it! And, by the way, next time maybe you don`t forget to back up before doing anything to your phone!

nmugurel2003 said:
I don`t think your phones are dead. I didn`t try it personally, but I`m sure you can restore your EFS back. Just you need to do some research, maybe you could start here:
https://www.google.ro/?gws_rd=ssl#safe=off&q=how+to+recover+efs+folder
Do not give up, read on end you will eventually do it! And, by the way, next time maybe you don`t forget to back up before doing anything to your phone!
Click to expand...
Click to collapse
I did back up. with both titanium backup and twrp but it is not working. And I dont think I will give up. I will format is all together and start over if i have to.
Do you think it will work if I format it entirely and start over?

dexterousyash said:
I did back up. with both titanium backup and twrp but it is not working. And I dont think I will give up. I will format is all together and start over if i have to.
Do you think it will work if I format it entirely and start over?
Click to expand...
Click to collapse
Glad to see you solved it!

[Q] Oneplus one not working

I updated my Oneplus One manually to the newest Version of CM12s. While flashing it, my Recovery (TWRP) chrashed. So to be sure I installed my freshly performed Nandroid Backup. But nothing helped. I couldnt connect with the Wifi, no SIM Cards were found, no Bluetooth Connectivity and it had Random Reboots. So i decided to flash back to Stock CM11s (the first ever released). But the Problems were the same afterwards. I flashed the Stock image via ADB and, after I found out nothing changed, via the Oneplus One Toolkit, but the Problems were still there. I also made a video on Youtube to show what happens and i hope that i can repair it and must not send it back to repair, because a repair would cost me up to 300€. So pls tell me a way to fix this Problem, because I really like this Phone:crying::crying::crying:
For the video search "Oneplus One not working" by the User "axel thegamer"

AxelWexel said:
I updated my Oneplus One manually to the newest Version of CM12s. While flashing it, my Recovery (TWRP) chrashed. So to be sure I installed my freshly performed Nandroid Backup. But nothing helped. I couldnt connect with the Wifi, no SIM Cards were found, no Bluetooth Connectivity and it had Random Reboots. So i decided to flash back to Stock CM11s (the first ever released). But the Problems were the same afterwards. I flashed the Stock image via ADB and, after I found out nothing changed, via the Oneplus One Toolkit, but the Problems were still there. I also made a video on Youtube to show what happens and i hope that i can repair it and must not send it back to repair, because a repair would cost me up to 300€. So pls tell me a way to fix this Problem, because I really like this Phone:crying::crying::crying:
For the video search "Oneplus One not working" by the User "axel thegamer"
Click to expand...
Click to collapse
Can't find your video, can you paste the link as text?

gsmyth said:
Can't find your video, can you paste the link as text?
Click to expand...
Click to collapse
i cant, because i made a new account here.
just search "oneplus one not working", then set "filter" on today and you will find it

AxelWexel said:
i cant, because i made a new account here.
just search "oneplus one not working", then set "filter" on today and you will find it
Click to expand...
Click to collapse
Ok found your vid, I see you have flashed the stock image files via ADB, have you done a full factory reset (wiping data) from the phone/TWRP? Its a bit worrying that flashing the stock image files didnt sort the issue. As it seems to be WiFi on/off that causes the reboot it would make me think it was to modem/radio but this should have been written again when you flashed the stock images.
@AxelWexel can you check in your Settings>About phone menu if your IMEI number is showing? Just in case your EFS has become corrupted. It definitely sounds fixable as if something has corrupted and needs wiped fresh.
EFS fix:
http://forum.xda-developers.com/oneplus-one/general/fix-people-corrupt-efs-mobile-data-t2836389
Also worth a shot, fixing corrupt partitions guide in ADB:
http://forum.xda-developers.com/oneplus-one/general/guide-identifying-fixing-corrupted-t2993500

gsmyth said:
Ok found your vid, I see you have flashed the stock image files via ADB, have you done a full factory reset (wiping data) from the phone/TWRP? Its a bit worrying that flashing the stock image files didnt sort the issue. As it seems to be WiFi on/off that causes the reboot it would make me think it was to modem/radio but this should have been written again when you flashed the stock images.
@AxelWexel can you check in your Settings>About phone menu if your IMEI number is showing? Just in case your EFS has become corrupted. It definitely sounds fixable as if something has corrupted and needs wiped fresh.
EFS fix:
http://forum.xda-developers.com/oneplus-one/general/fix-people-corrupt-efs-mobile-data-t2836389
Also worth a shot, fixing corrupt partitions guide in ADB:
http://forum.xda-developers.com/oneplus-one/general/guide-identifying-fixing-corrupted-t2993500
Click to expand...
Click to collapse
Thx for the Links and i tried to watch on my phone and there is no imei number. I also did a full wipe after i found the issues. I also tried it via the Toolbox to flash the stock rom back but it hadnt change anything. But I will look the links you postet and reply if anything has changed. But now thx again:good:
P.S: I renamed the Video to "Oneplus One not working (23.06.2015)" to find it more easily
Edit 1: The Second Link with fixing corrupt partitions via adb wont work for me because i dont have root but my bootloader is unlocked. so i cant find the root acsess for adb in the developer options
Edit 2: I installed color os like the link said, done everything it said, but still no wifi, bluetooth and no sim card detection:crying:. Luckily the random reboot stopped Could you again help me further more because it seemed to help
Edit 3: I went back to cm11s, because in color os when i turned the phone off it turned on again, the connectivity was not there. After the install it became worse with the random reboots. I think i must send it to repair and pay 300€:crying::crying::crying::crying:

No mobile data after flash. Nothing will bring it back

>> Partial solution was found; still looking for the root of the problem. <<
I recently decided to take the plunge and root my OnePlus One and install sultanXDA's CM 13 ROM on it. It was all going well until I booted up into the ROM and discovered that I couldn't get any mobile data. Everything else was working, calling, texting, wifi, but mobile data seemed to refuse to work. Since I initially flashed sultan's ROM with TWRP 3.0.0, I suspected it was a problem with my modem. Though unable to install TWRP 2.8.6.0 to re-flash everything, I did still flash a new modem via ADB. This didn't help.
I have tried many things to fix this. I rebooted/reflashed. I flashed different ROMs. I tried flashing on TWRP 2.8.6.1, though I believe that one has the same modem problem as the versions after it. As mentioned above I tried flashing a modem over ADB. I took out and re inserted my SIM card. In the end, I tried this guide here to restore my phone to it's original state. The guide flashes the stock versions of everything via ADB. Though it did return me to unrooted COS 12.1, it was not able to resolve my data problem.
After the total reset, all I can think that could be causing it is a hardware problem or that it is caused by something not reset in the 100% restore above.
If any of y'all can help my solve this, or at least offer insight, I would be very grateful.
Preemptive Edit I Guess: This thread was just suggested to me while writing this. I'm going to try the solution here and report back. It's OnePlus' reset to stock method. I'm not expecting much after my first 100% reset attempt, but we'll see.
EDIT: Ok, so the solution above fixed my problem... (edit again: turned out to only be a partial solution. See below.)
I would feel really dumb right now if it weren't for the fact that I slaved over this problem for a good ~8 hours before writing this post. Anyways, I'm not sure how to delete this post or mark it as solved. Sorry for the trouble y'all.

Never delete this post !!
I have the same problem, and I spent much more time to find a solution.
I will try this and will update.
Is it a clean stock rom?
Edit:
Didn't help for me ..
Still the same problem, No mobile internet connection.
Thx anyway.

Yeah, actually I was too hasty is identifying this as the solution. For me, the stock reset brought me back to CM 11 which didn't have a problem with mobile data. But if I try to flash a later ROM or update via OTA, the problem returns. I'm still trying to figure out what is causing it. The only information I can find points to it being a modem problem or APN problem, but I'm sure I have sufficiently checked both of those already.
Either way, I'll keep looking. If I find something I'll return here with it. Good luck

arkasa said:
Yeah, actually I was too hasty is identifying this as the solution. For me, the stock reset brought me back to CM 11 which didn't have a problem with mobile data. But if I try to flash a later ROM or update via OTA, the problem returns. I'm still trying to figure out what is causing it. The only information I can find points to it being a modem problem or APN problem, but I'm sure I have sufficiently checked both of those already.
Either way, I'll keep looking. If I find something I'll return here with it. Good luck
Click to expand...
Click to collapse
Try this:
1) Download the latest fastboot images from here: http://forum.xda-developers.com/oneplus-one/general/official-cm11s-roms-ota-updates-t2906746
2) Go here and follow step #8: http://forum.xda-developers.com/oneplus-one/general/guides-bacon-timmaaas-how-to-guides-t2839471
3) Then follow step #2 to install a new recovery (you need to make sure to use TWRP 3.0.0 or the unofficial TWRP if you want to flash modems/firmwares correctly)
4) Download the latest ROM of your choice and install via your recovery

ryanmat said:
Try this:
1) Download the latest fastboot images from here: http://forum.xda-developers.com/oneplus-one/general/official-cm11s-roms-ota-updates-t2906746
2) Go here and follow step #8: http://forum.xda-developers.com/oneplus-one/general/guides-bacon-timmaaas-how-to-guides-t2839471
3) Then follow step #2 to install a new recovery (you need to make sure to use TWRP 3.0.0 or the unofficial TWRP if you want to flash modems/firmwares correctly)
4) Download the latest ROM of your choice and install via your recovery
Click to expand...
Click to collapse
I gave this a try, but booting up after step 3 I still had the same problem. If I understand this method correctly, I think it is essentially the same as the other full restore methods I tried.
I think I may have found the problem though. I was looking at OnePlus' guide to installing OxygenOS. In it they said, "do not try to flash this build through TWRP. You will most likely lose your radio and IMEI which means a trip to our customer support." At this point I have repeatedly reset/restored my modem/radio so I don't think that is the problem, but I haven't seen anything about IMEI before. The IMEI is apparently stored in the EFS partition which as far as I can tell, is not touched by any of the restore methods I have tried. I took a look at my IMEI (about phone -> status) and it turns out my IMEI SV is 00. It's supposed to be a 16 digit number. I found a guide to fixing it, but I think I will just contact OnePlus customer support first.
I'll be back later with my results.

arkasa said:
I gave this a try, but booting up after step 3 I still had the same problem. If I understand this method correctly, I think it is essentially the same as the other full restore methods I tried.
I think I may have found the problem though. I was looking at OnePlus' guide to installing OxygenOS. In it they said, "do not try to flash this build through TWRP. You will most likely lose your radio and IMEI which means a trip to our customer support." At this point I have repeatedly reset/restored my modem/radio so I don't think that is the problem, but I haven't seen anything about IMEI before. The IMEI is apparently stored in the EFS partition which as far as I can tell, is not touched by any of the restore methods I have tried. I took a look at my IMEI (about phone -> status) and it turns out my IMEI SV is 00. It's supposed to be a 16 digit number. I found a guide to fixing it, but I think I will just contact OnePlus customer support first.
I'll be back later with my results.
Click to expand...
Click to collapse
Are you flashing each of the extracted .img files from fastboot, exactly like the guide shows, or are you doing something else?

ryanmat said:
Are you flashing each of the extracted .img files from fastboot, exactly like the guide shows, or are you doing something else?
Click to expand...
Click to collapse
Yep, I ran each command listed in the guide and my phone was definitely in fastboot. Each command had a collections of "OKAY"s and ended with a "finished", which I assume means it executed as expected.

I have tried 2 different sim cards in my OPO (of two different companies, one of them as mine), and mobile data worked perfectly. Is it possible that my phone is ok and the problem happened in the sim card?
AND... my IMEI SV is 00 too. please update here if it has a connection.
Thank you !

omersa99 said:
I have tried 2 different sim cards in my OPO (of two different companies, one of them as mine), and mobile data worked perfectly. Is it possible that my phone is ok and the problem happened in the sim card?
AND... my IMEI SV is 00 too. please update here if it has a connection.
Thank you !
Click to expand...
Click to collapse
I'm not entirely sure what you're saying. Did it not work with the first SIM card, but it worked with the second?

Mobile data problem was occured (to me), after I rooted my OPO and tried to flash a new rom.
I still can't understand how it convinced my sim card, but the fact is that I tried two (to be sure) other sim cards which are not mine, and mobile data worked well.
When I returned my original sim card, problem started again.
So I am almost sure that sim card has a connection, but can't understand why. And why it happend precisely now, cause it worked well over two years.

omersa99 said:
Mobile data problem was occured (to me), after I rooted my OPO and tried to flash a new rom.
I still can't understand how it convinced my sim card, but the fact is that I tried two (to be sure) other sim cards which are not mine, and mobile data worked well.
When I returned my original sim card, problem started again.
So I am almost sure that sim card has a connection, but can't understand why. And why it happend precisely now, cause it worked well over two years.
Click to expand...
Click to collapse
sorry to intrude...but looks like mine problem too...but no connection with provider at all...and it worked 1 month normal (stock opo)..
could u flash the modem to resolve this problem?
jpvr
http://forum.xda-developers.com/one...e-plus-one-t3030545/post65841063#post65841063

Why don't you flash twrp flashable modem?
If your network is present but no data , mostly data service problem. Are you pay your mobile bills ?
Are you activate data services ?
Try this
https://www.androidfilehost.com/?w=files&flid=28032

drmuruga said:
Why don't you flash twrp flashable modem?
If your network is present but no data , mostly data service problem. Are you pay your mobile bills ?
Are you activate data services ?
Try this
https://forums.oneplus.net/threads/cos-12-master-fix-thread.307446/
Click to expand...
Click to collapse
...yes i paid my bills ..
- my network connection to provider is dead...it worked perfecly for 1 month out of the box (see original posting for detailed action i took) this thread is about lack of data connection...but also MODEM related???
- tried the brand new simcard in my old Samsung sII... works perfetly, network connection with provider, data connection and calling..so no simcard problem

Long shot. Change any APN settings from IPv6 to IPv4. That was my problem when I had text/voice but no data.

I made a post on this and then called att gophone, due to seeing other sims working on this thread, and he helped me to fix. Posting my fix here in case others with isue find this post instead of mine.
Turned off wifi.
Turned off cellular data.
Went to APN and changed the apn (ATT Go Phone) from pta to nxtgenphone.
Turned on cellular data.
Finally had H+ above he signal bar, but had an X inside the bar.
Don't know if he did anything on his end, but the X went away after a couple of minutes.
Data was working, albeit kinda slow.
Turned off phone for three minutes per ATT rep.
Rebooted.
Data still slow, but it is at least working. Thinking I need to flash different modem. Battery usage has been higher the last day or two since I flashed c7 anyways.

Blank IMEI, Unknown Baseband ,Unable to read sim ;after official OTA to Marshmallow

Hi! I am using a LG Nexus 5. Previously it ran on Android Lollipop , after which I tried to update to Android Marshmallow using the official OTA update. Unfortunately, after this update, my phone stopped reading my sim card right from the first bootup. On dialing *#06#, I receive a blank space instead of the IMEI value. further, the baseband is listed as unknown in the phone settings. Although the functionalities other than those of the baseband processor (such as calling, sms , gps) run flawlessly. I have never played around with this phone so it has a locked bootloader and does not have a root access etc.
I have been scouring the internet for around 2 months now but could not find anything conclusive , so I decided to start a fresh thread here.
What are my best options to restore my phone-turned-tablet back to a phone with functional cellular capabilities?

So sad, i hope u got it fixed, i did an EFS backup, it's dangerous to not have one in case of EFS partition get wiped :/

adrianocolvero said:
So sad, i hope u got it fixed, i did an EFS backup, it's dangerous to not have one in case of EFS partition get wiped :/
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No, I have not been able to find out yet how to proceed. Please suggest me how to take the EFS backup and how should i proceed further after taking the backup

same problem
I have a Nexus 5, did the OTA Marshmallow update, now having the same issues you mentioned.....Blank IMEI #, Unable to read sim. Everything else works, except calls and sms, right now its a tablet too. If you have found a fix let me know. Thanks

You guys may want to check out the below post. Hope it helps.
http://forum.xda-developers.com/goo...efs-backup-t2769023/post60421668#post60421668

No root access and a locked bootloader.. and still semi bricked during an official OTA? I wondered how many more are having this problem unreported?

From what I have read so far, does seem somewhat common. If I would have known about backing up the EFS partition, I would have. I had the phone for two years unrooted and no problems at all.
Lim Wee Huat said:
No root access and a locked bootloader.. and still semi bricked during an official OTA? I wondered how many more are having this problem unreported?
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