Database Info

"Key Driver Not Found.. " on Bootloader 4.2.1

So this morning my brother was using his TF300T in its dock. He undocked it and the screen went blank. Screen was still on but nothing displayed. I rebooted it for him (volume down and power button for 10s). After a minute of it powered on the screen went blank again, so I rebooted it again, but this time the Asus splash screen displays and the lock screen flickers before quickly going blank.
Thought a reinstall of the ROM would fix the problem but I now can't even boot into recovery or fastboot! Had no problem the first time I rebooted and selected cold-boot in the bootloader options. With the tablet on and screen blank I plugged it into a PC and Win7 detected and installed the proper drivers (I think). ADB commands seem to work, but the command to boot into bootloader only resets the tablet. Fastboot command does not work. Also noticed the below message flash before a flicker of bootloader options are shown. The PC seems to have access to the internal storage (I can see folders from the tablet) when plugged in via USB.
"Key driver not found.. Booting OS
Android cardhu-user bootloader <2.00 e> released by "US_ePad-10.6.1.8-20130PPt" A03"
Could it be a hardware issue? I ask because I see similar problems with the Asus splash screen indicative of a logic board problem when diagnosing a PC (images pixelated)...

MaMMiTs said:
So this morning my brother was using his TF300T in its dock. He undocked it and the screen went blank. Screen was still on but nothing displayed. I rebooted it for him (volume down and power button for 10s). After a minute of it powered on the screen went blank again, so I rebooted it again, but this time the Asus splash screen displays and the lock screen flickers before quickly going blank.
Thought a reinstall of the ROM would fix the problem but I now can't even boot into recovery or fastboot! Had no problem the first time I rebooted and selected cold-boot in the bootloader options. With the tablet on and screen blank I plugged it into a PC and Win7 detected and installed the proper drivers (I think). ADB commands seem to work, but the command to boot into bootloader only resets the tablet. Fastboot command does not work. Also noticed the below message flash before a flicker of bootloader options are shown. The PC seems to have access to the internal storage (I can see folders from the tablet) when plugged in via USB.
"Key driver not found.. Booting OS
Android cardhu-user bootloader <2.00 e> released by "US_ePad-10.6.1.8-20130PPt" A03"
Could it be a hardware issue? I ask because I see similar problems with the Asus splash screen indicative of a logic board problem when diagnosing a PC (images pixelated)...
Click to expand...
Click to collapse
It is unlikely windows installed the proper drivers for adb and fastboot. The drivers for accessing the internal sdcard yes.
See my signature for installing proper drivers in windows 7 and another for entering the bootloader after you have the proper drivers.
When I have seen that message it does not relate to hardware but software.
I don't suggest plugging and unplugging the dock when powered.

tobdaryl said:
It is unlikely windows installed the proper drivers for adb and fastboot. The drivers for accessing the internal sdcard yes.
See my signature for installing proper drivers in windows 7 and another for entering the bootloader after you have the proper drivers.
When I have seen that message it does not relate to hardware but software.
I don't suggest plugging and unplugging the dock when powered.
Click to expand...
Click to collapse
Will try what you suggested, but does it matter that I'm using the same PC I used to initially fastboot TWRP to the tablet? I thought once the driver is installed it there would be no need to re-install the driver...

MaMMiTs said:
Will try what you suggested, but does it matter that I'm using the same PC I used to initially fastboot TWRP to the tablet? I thought once the driver is installed it there would be no need to re-install the driver...
Click to expand...
Click to collapse
It will probably be ok. I was going by your comment "I plugged it into a PC and Win7 detected and installed the proper drivers (I think)"

tobdaryl said:
It will probably be ok. I was going by your comment "I plugged it into a PC and Win7 detected and installed the proper drivers (I think)"
Click to expand...
Click to collapse
Yeah. My problem is I can't get to fastboot mode on the tablet itself, and based on what I saw on another thread it seems like I'm going to have to replace the mainboard .

MaMMiTs said:
Yeah. My problem is I can't get to fastboot mode on the tablet itself, and based on what I saw on another thread it seems like I'm going to have to replace the mainboard .
Click to expand...
Click to collapse
OK.
Good Luck!

I unplug mine and reconnect all the time when on. Never had a issue.
Sent from magical jelly bean.

My brother's TF300T is back up and running!
As a last resort I opened it up to disconnect the battery. Still could not get into fastboot, so I left the battery plugged in and let the battery run out. After 48 hours of the battery being completely dead I charged it fully to see if I could do anything. Battery LED indicator was green and the first thing I noticed was that the unit was still off. (I wasn't able to completely shut it down before letting the battery completely drain). I powered it on thinking it would display a blank screen, but it powered up as usual! Everything seems to be working. I immediately flashed CROMI-X 4.3b6 on it (what my brother originally wanted me to do).
Thought I'd post this as a last resort hope for those who think they may have bricked their machine. I do recall completely draining the battery then waiting over 24 hours as a solution for one of the many machines I've hacked. Just thought disconnecting the battery would achieve the same purpose. Guess I was wrong . Hopefully this is a solution for someone else out there who may have bricked their machine. Sure doesn't hurt to try .
I'm actually mystified as to why this worked. Anyone know? I'm guessing completely draining the battery reset whatever was inside. I also have noticed more users have reportedly bricked their machines after Android 4.2.1. Coincidental? Thank God I'm perfectly happy with Android 4.1.1 based CROMI v3.4.6 .

[Q] Bricked Android Tablet, Please help me.

I accidentally installed the wrong version of cwm on a softwinerEvb A13 model android 4.1.1 tablet. (I know dumb mistake - I have a few different versions I downloaded for different devices and I accidentally grabbed and flashed the wrong one with flashify app. Now I'm bricked as far as I know. I rebooted and it booted normally fine. Then I tried to boot into recovery (at this point I hadn't realized it was the wrong cwm version). The tablet just went to the boot screen and sits there. I held the power button to power down. devices turns off. then I tried booting back to normal and it gives me the same boot screen and sits there. I've tried every button combination and it just sits on the boot screen.
Any help or advice is much appreciated. Thank you very much.
ADB won't recognize device. It just says "error: device not found".

Of any mobilr bricks there are two ways to repair,one is from adb and other is from recovery,but in ur case these two are not working.
Somehow try buttons combo and enter the mobile,such that ur pc recognizes the device,thats it problems solved...:thumbup:
SENT FROM MONSTER ! ! !
HIT THANX OR I WILL JUST
CRY...

sounds like you're in big trouble man , just search and you'll find answers , if booting and restoring is no use idk how lol.

BRICKED 7inch Irola Tablet...PLEASE HELP
I am in DIRE need of some help with my tablet. I received this irola dx752 tablet bricked and cannot fix it for the life of me. I am able to hold power and volume up and get into recovery system version 4.2.01. I Have tried a factory reset and a wipe system cache and the tablet just reboots to the green robot with and exclamation mark. If I press volume up, it brings me back to the system recovery. Now i am not very versed in ADB but I tried to sideload just about every firmware I could find for an a13 allwinner a8 cortex 7inch tablet, since the irola website has taken down its firmware. Also, fastboot will not work on this tablet whatsoever (it just says waiting for device) when i enter any command. I have never seen this tablet boot into a rom of any kind and therefore cannot tell if USB Debugging was ever enabled. I also Have tried different drivers but the one that seem to hold is the Android ADB Interface. CAN ANYONE PLEASE GIVE ME SOME SUGGESTIONS OR SOME HELP? It would be greatly appreciated. Thank you.

[Q] Stuck at bootlogo

Hi,
I got this tablet from a friend, and it's stuck at the boot logo. I've tried hard reset, reset via recovery, nothing seems to work.
How can I flash the latest official rom?
Can't seem to find a tool for it, and Asus suggest to flash with the tablet itself, but that's not possible for now.
Anyone?
Thx!

http://forum.xda-developers.com/showthread.php?t=1688012
Easyflasher to flash TWRP recovery > copy ROM to MicroSD card, flash ROM

Thanks! I can't seem to get him into APX mode, what is the exact procedure?

Connect the tab to USB > PC first
Power Off the Tab
Hold Volume Up & Power
Nothing will appear on the Tab screen, but the PC should sound the USB connect noise / device manager will show it has connected - only takes a few seconds to enter APX mode

I've tried that, doesn't seem to recognize it . Would you help me via IM of some sort?

It`ll be the drivers most likely, open device manager when its connected and in APX mode, and manually update the drivers using the Universal Naked Driver from the Easyflasher site
I don't have any IM installed unfortunately but I`ll help you out here

Ok, that would be wonderful. The problem is, I don't know when it's off. I can't get it to shut down, it keeps rebooting. I'm monitoring dev manager with sound high, but it's not coming up. Cable is working, because it will charge. Using the original cable. (Windows 7 x64)

Best thing to do would be connect it to the PC, then press and hold Power until it shuts off, then try for APX mode - you might even be able to enter APX from a powered on state by holding the same button combo, but Ive not tested that myself
And a cable that charges doesn't automatically mean it will work for Data, they use different pins, some for power and some for data, if the data pins are damaged, it will still charge

I can't seem to get it working . Any other ways to flash it?

Not without being able to get it to boot - you'll need APX mode to do anything in the state it's in now
A bad cable is a common problem though, might be worth grabbing another one from eBay

To bad. I'll try and let it drain till it's empty, and fully charge it then. Just ordered another cable.
Thx for the help!

If the System / Data partitions are corrupted, which generally causes the boot loop, then draining and recharging won't help
Plus be careful not to drain the battery to 0%, their design prevents them from recharging if they hit 0% - many people have had to buy new batteries after not using their tab for a few months and letting it drain completely
Good luck, so long as there is no hardware damage, once you have a working cable it should be pretty straight forward to get TWRP recovery and a new ROM flashed to it
Might be worth trying your current cable on another PC too

Thanks for the headsup! Will try!

Hello everyone,
Not to thread jack but I have a similar problem and instead of opening a new thread I decided to revive this one.
I have a similar problem that my TF101 has been working flawlessly for many years. It is rooted and was running 4.3 ROM. As of a couple of days ago it just won't boot at all. It has been stuck at the NVidia screen and just sits there. I tried to enter recovery mode by using volume(-) + power and the unit presents the TEAMWIN logo and just loops as well by showing the TWRP screen (3 seconds) then going blank for a second then showing TWRP screen again in a cycle.
I downloaded and tried Easyflasher and Brks toolkit and nothing can complete the flash. Tried different installed drivers as well. I can enter MTP mode which the computer can see the device but the manufacturer name and model are not-recognized. I can also enter APX mode but while trying to flash anything I get an error message (error, cannot flash bootloader) and the computer dings (device disconnects).
I have been trying for a days now and have run out of ideas.
Has the unit finally bit the dust? Does any one out there have any more ideas or suggestions on what to try next?
TIA for any help provided.

Anyone with any sort of help on my previous post? Time to retire it for real this time?
TIA
Sent from my VisionX powered SM-N900T.

Jayster0966 said:
Anyone with any sort of help on my previous post? Time to retire it for real this time?
TIA
Sent from my VisionX powered SM-N900T.
Click to expand...
Click to collapse
Have you tried a different / new cable in-case that's the reason all the flashing attempts and computer recognising the unit are failing ?

[Q] [SOLVED] Off-brand tablet bricked after "adb reboot bootloader"

Hi,
I have an iRulu (some off-brand Chinese tablet that is also somewhat branded as Allwinner) 9.7" tablet. I was going install a recovery and try to learn how to compile a ROM for it but things went wrong at step one. I hooked it up to my computer (running Arch linux) and got ADB to recognize the device. I typed "adb reboot bootloader" to get into fastboot and see if the bootloader was unlocked, but when it rebooted it just got stuck on the logo screen and was not responsive to fastboot and adb no longer recognized its presence. I haven't been able to find any other examples online of that command bricking a device. As far as I can tell, none of the normal button combinations work to get to recovery or anything like that. It's not really a bootloop because it doesn't restart and try to boot again. It's just frozen and I can't find my way in. I found a forum that said to disconnect the battery for 30 seconds but it's soldered in (I'm comfortable desoldering and resoldering but I'd prefer another solution). Any ideas on how to recover the situation? Thanks in advance!

830hobbes said:
Hi,
I have an iRulu (some off-brand Chinese tablet that is also somewhat branded as Allwinner) 9.7" tablet. I was going install a recovery and try to learn how to compile a ROM for it but things went wrong at step one. I hooked it up to my computer (running Arch linux) and got ADB to recognize the device. I typed "adb reboot bootloader" to get into fastboot and see if the bootloader was unlocked, but when it rebooted it just got stuck on the logo screen and was not responsive to fastboot and adb no longer recognized its presence. I haven't been able to find any other examples online of that command bricking a device. As far as I can tell, none of the normal button combinations work to get to recovery or anything like that. It's not really a bootloop because it doesn't restart and try to boot again. It's just frozen and I can't find my way in. I found a forum that said to disconnect the battery for 30 seconds but it's soldered in (I'm comfortable desoldering and resoldering but I'd prefer another solution). Any ideas on how to recover the situation? Thanks in advance!
Click to expand...
Click to collapse
When you open the back cover, do you see the board number? You can try searching for firmware using the number, and flashing it. Mine was stuck in bootloop for months before i figured it out(i own a ubislate 7c+ edge, a11 firmware worked for me).
Sent from my GT-I9082 using XDA Free mobile app

NoobInToto said:
When you open the back cover, do you see the board number? You can try searching for firmware using the number, and flashing it. Mine was stuck in bootloop for months before i figured it out(i own a ubislate 7c+ edge, a11 firmware worked for me).
Sent from my GT-I9082 using XDA Free mobile app
Click to expand...
Click to collapse
Thanks that's a great idea. Might not solve the problem to know the firmware, but more information is always helpful.

OK, I solved this. Here's what I did:
- Let the tablet die. All the way. After I left it on that stupid boot screen it was stuck on until it died, I left it another week just sitting there.
- Plug in the power connector and the micro usb connector.
- Turn it on once it gets charged enough that it's willing to start.
- Move the USB connector to the USB-to-go (HOST) spot while still connected to your computer. This crashes the device from some kind of voltage protection mechanism.
I'm not sure exactly what happened but after that the device started just fine. I think the voltage protection mechanism might have kicked it out of "boot to bootloader" mode, where I think it was frozen, and into actual boot mode. I wouldn't necessarily recommend this solution since I put the actual hardware of my computer and the tablet at risk, but I figured my laptop was old and my tablet was bricked so there wouldn't be any huge loss.
Anyway, I'm marking this as solved. If anyone has this happen to them and my solution actually works for you, let me know. I'd get a huge kick out of hearing someone else follow my stupidity. Good to have my tablet back!

Sisonke= We are on the same path in my language
i am currently having the same situation RIGHT NOW. Loved messing with ADB and its ....functions... also typed adb reboot-bootloader and guess what i got.. Stuck at the boot face. lol:laugh: but im gonna take our advice, if you say draining the power is the key...well i find no harm in cutting the main battery source for a while and then reconnecting it again. If this procedure doesn't work...I'll have to do it your way. Crossing fingers ..hope it works. email me wen u get this. [email protected]:angel:

[Completed] Potentially ruined my phone - help please!

So this morning I was trying to unroot my phone and return it to stock. I found a ROM and was going to use TWRP to flash it on and then replace the recovery with stock... except the ROM I found soft bricked my phone. OK not ideal but found a work around in the Sideload function.
I downloaded ViperROM and it was copying across but got stuck on 7% for ages. The screen was black but vibrating to the power button. After ages I assumed it has crashed so I yanked out the cable and tried to turn my phone off and on again... it doesn't turn off. It just vibrates away when I press the top button. So not only do I have a phone with no OS, I can't get it to turn off and on again.
When I reconnect it to my computer and enter adb devives I can see it's still in Sideboot mode. When I try to "adb reboot bootloader" I get "error: closed".
Any ideas on how I can at least get my phone to load the recovery again?
Please help!

Boxy89 said:
So this morning I was trying to unroot my phone and return it to stock. I found a ROM and was going to use TWRP to flash it on and then replace the recovery with stock... except the ROM I found soft bricked my phone. OK not ideal but found a work around in the Sideload function.
I downloaded ViperROM and it was copying across but got stuck on 7% for ages. The screen was black but vibrating to the power button. After ages I assumed it has crashed so I yanked out the cable and tried to turn my phone off and on again... it doesn't turn off. It just vibrates away when I press the top button. So not only do I have a phone with no OS, I can't get it to turn off and on again.
When I reconnect it to my computer and enter adb devives I can see it's still in Sideboot mode. When I try to "adb reboot bootloader" I get "error: closed".
Any ideas on how I can at least get my phone to load the recovery again?
Please help!
Click to expand...
Click to collapse
Hi, thank you for using XDA assist.
You did not mention the device name. However,
There is a general forum for android here https://forum.xda-developers.com/android/help where you can get better help and support if you try to ask over there.
Good luck.

Vivek_Neel said:
Hi, thank you for using XDA assist.
You did not mention the device name. However,
There is a general forum for android here https://forum.xda-developers.com/android/help where you can get better help and support if you try to ask over there.
Good luck.
Click to expand...
Click to collapse
Ahh sorry. My fault, I thought this was the Android one. And completely dumb move on forgetting the phone! I'l try my luck over there.
Thanks,