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Downgrade bootloader despite efuses so I can switch

I have a Sprint-branded S7. It's unlocked. I want to switch to T-Mobile.
Sprint changed its S7 bootloader to v5 in November 2017. All other carriers, including T-Mobile, are on bootloader v4 or earlier.
The problem: You can't flash to an older-version bootloader. You'll just get an error. The phone has efuses that prevent it.
Are there any workarounds?
Specifically, I want to switch this S7 from Sprint's G930PVPS5BRA1 to T-Mobile's G930TUVS4BRA1 (bootloader version emphasized).

No work arounds I've ever seen, US snapdragon models are all bootloader locked which prevents you doing any major modifications at a firmware level.
You'll either have to wait for a v5 of the firmware you want, or try the carrier unlocked G930U v5 firmware which might work better with T-Mobile.
I believe this is also the same for the unlocked bootloader on Exynos models, but only if you get the newest drag firmware version.

Beanvee7 said:
No work arounds I've ever seen, US snapdragon models are all bootloader locked which prevents you doing any major modifications at a firmware level.
You'll either have to wait for a v5 of the firmware you want, or try the carrier unlocked G930U v5 firmware which might work better with T-Mobile.
I believe this is also the same for the unlocked bootloader on Exynos models, but only if you get the newest drag firmware version.
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Click to collapse
Unlocked is also on bootloader v4: https://www.sammobile.com/firmwares/galaxy-s7/SM-G930U/. That is why I suspect this v5 bootloader is a trick by Sprint to frustrate switching.

Booloaders are all locked on US S7s you can not switch Stock ROMs
You could SIM unlock and use a T-Mobile SIM though (paid)
Or sell that phone and buy a tmobile one

*Detection* said:
Booloaders are all locked on US S7s you can not switch Stock ROMs
You could SIM unlock and use a T-Mobile SIM though (paid)
Or sell that phone and buy a tmobile one
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Click to collapse
This phone has the domestic unlock by Sprint, so I can switch stock ROMs. I did exactly that last summer when Sprint and T-Mobile's ROMs both had v4 bootloaders.
Because it is unlocked, you are right that I can also put in a T-Mobile SIM while it has the Sprint ROM. However, it will not see all T-Mobile bands until I put T-Mobile firmware on it. I noticed that last summer, and there are other anecdotal reports of this on the internetzors.

novasource said:
This phone has the domestic unlock by Sprint, so I can switch stock ROMs. I did exactly that last summer when Sprint and T-Mobile's ROMs both had v4 bootloaders.
Because it is unlocked, you are right that I can also put in a T-Mobile SIM while it has the Sprint ROM. However, it will not see all T-Mobile bands until I put T-Mobile firmware on it. I noticed that last summer, and there are other anecdotal reports of this on the internetzors.
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Pretty certain that all bootloaders on the US model S7s are locked meaning you cannot switch stock ROMs, other than Verizon to the G930U, maybe others to that U firmware, but I don't own the snapdragon variant so just going on what I've read here on XDA
All Snapdragon US S7s are bootloader locked, meaning no custom anything
As for certain bootloaders of each stock ROM I don't know
But I do know SIM unlock and bootloader unlock are two completely different things, switching from one carrier ROM to another does not unlock the SIM to that carrier

*Detection* said:
Pretty certain that all bootloaders on the US model S7s are locked...
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They are locked against unauthorized/custom software, but there is nothing that stops you from putting authorized software on them. As all US variants are hardware-identical, all carrier ROMs are by definition authorized on any.

novasource said:
They are locked against unauthorized/custom software, but there is nothing that stops you from putting authorized software on them. As all US variants are hardware-identical, all carrier ROMs are by definition authorized on any.
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I see, but what would be the point of switching from Sprint to T-Mobile stock ROM?
Surely just different OEM bloat?

*Detection* said:
I see, but what would be the point of switching from Sprint to T-Mobile stock ROM?
Surely just different OEM bloat?
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While the hardware supports all bands, the ROMs do not have all bands enabled. From personal experience last summer, if you have the Sprint ROM on the phone, your phone will not see all T-Mobile bands. There are plenty of anecdotal reports of this on the internet.

novasource said:
While the hardware supports all bands, the ROMs do not have all bands enabled. From personal experience last summer, if you have the Sprint ROM on the phone, your phone will not see all T-Mobile bands. There are plenty of anecdotal reports of this on the internet.
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I was under the impression that only SIM unlocking would solve that?
So you are saying that by managing to flash from Sprint to T-Mobile, a Sprint S7 is now able to use the T-Mobile network without a SIM unlock ?

*Detection* said:
I was under the impression that only SIM unlocking would solve that?
So you are saying that by managing to flash from Sprint to T-Mobile, a Sprint S7 is now able to use the T-Mobile network without a SIM unlock ?
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Click to collapse
SIM unlocking only appears to permit you to put your phone on another network. It does not appear to enable all your phone's bands. To enable another network's bands, you appear to have to switch ROMs. If there's another way of doing that, I'm interested!

novasource said:
SIM unlocking only appears to permit you to put your phone on another network. It does not appear to enable all your phone's bands. To enable another network's bands, you appear to have to switch ROMs. If there's another way of doing that, I'm interested!
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Click to collapse
My guess is you would first need to perform the actual SIM unlock, and then move over to the preferred network ROM to have 100% of their bands and abilities
If your phone was originally on Sprint, and you managed to flash to T-Mobile, my guess is that your T-Mobile SIM would still not work until you SIM unlocked
CSC change is what determines which features work and don't, for example on o2 CSC I can get WiFi calling, but with XEU (also UK ROM) I cannot, even though my carrier is o2, basically I bought the phone on XEU but unless I switch manually over to O2 CSC I cannot use that feature

*Detection* said:
My guess is you would first need to perform the actual SIM unlock, and then move over to the preferred network ROM to have 100% of their bands and abilities
If your phone was originally on Sprint, and you managed to flash to T-Mobile, my guess is that your T-Mobile SIM would still not work until you SIM unlocked
CSC change is what determines which features work and don't, for example on o2 CSC I can get WiFi calling, but with XEU (also UK ROM) I cannot, even though my carrier is o2, basically I bought the phone on XEU but unless I switch manually over to O2 CSC I cannot use that feature
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Click to collapse
Yes. Another way of putting this is that SIM unlock and band unlock are different. Sprint can unlock the SIM and let me put other carriers' SIMs in my phone. However, that doesn't unlock all the bands. That is only doable by flashing that carrier's ROM. Due to Sprint's curious choice to upgrade its bootloader, I am locked out of doing that.
I have previously been in a state where my CP was from a different-version SM-G930U ROM, while the rest was from an SM-G930P ROM, and I got repeated "Security notice" warnings from the Samsung software.

HELP
Beanvee7 said:
No work arounds I've ever seen, US snapdragon models are all bootloader locked which prevents you doing any major modifications at a firmware level.
You'll either have to wait for a v5 of the firmware you want, or try the carrier unlocked G930U v5 firmware which might work better with T-Mobile.
I believe this is also the same for the unlocked bootloader on Exynos models, but only if you get the newest drag firmware version.
Click to expand...
Click to collapse
I am somewhat experienced in this but not enough to be sure. I have sm-g30U factory unlocked by sam and got oreo update and hate. How may I check my versions or rather where might I find the proper software to downgrade to nougat . I dont understand why people keep saying "930U sprint, or vzw" . When its unlocked its not any carrier only the carrier you happen to use as its a dual sim right ? though today im with vzw i may not be tomorrow. Anyway can i flash backwards , I saw a few videos where it was done on sammobile and if not I would love to get any info in rooting it to help my battery not liking the oreo so i can help at least with bloatware. any help would be appreciated

nocamp said:
I dont understand why people keep saying "930U sprint, or vzw"d
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There's two types of unlock.
* Bootloader unlock, which allows you to modifies the phones boot partition. It's required for custom ROM's and recovery.
* Carrier unlock, which is just whether your phone allows any SIM or only a specific carrier.
The G930U is carrier unlocked, you can use any SIM, but it's still bootloader locked like every other US model S7, which means no boot modifications.
As a result you can't rollback the G930U because of the locked bootloader, and you can root it but only but using an engineering bootloader which comes with many side affects.

Does only the number matter or does also the letter? For example, say Im deciding between U5 and S5, how would the efuse work?

DeeXii said:
Does only the number matter or does also the letter? For example, say Im deciding between U5 and S5, how would the efuse work?
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Yes just the number , cell carriers tend to use the letter S while Samsung unbranded tend to use the letter U. But the number tells you the version boot loader .

Will Verizon lock a phone if it's unlocked?

Getting an Unlocked Pixel 2 off EBay.
Once I unlock the bootloader, and put in my Verizon sim.......will Verizon lock my bootloader?
z

I don't think any carrier has control over locking the bootloader. They can however keep you from unlocking it, just not the other way around

zardiw said:
Getting an Unlocked Pixel 2 off EBay.
Once I unlock the bootloader, and put in my Verizon sim.......will Verizon lock my bootloader?
z
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As long as it actually was through Google and not a Verizon one you will be fine. Make sure it's not just carrier unlocked, since the Verizon ones will still be considered unlocked due to being able to use it on other carriers.

Keithn said:
As long as it actually was through Google and not a Verizon one you will be fine. Make sure it's not just carrier unlocked, since the Verizon ones will still be considered unlocked due to being able to use it on other carriers.
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The op is talking about bootloader being unlocked and your talking about the carrier/sim lock... Verizon pixels that were on a certain firmware were able to have their bootloader unlocked, and then it was patched. So pretty much all Verizon pixel 2 are not able to have the bootloader unlocked. Pixels straight from Google are able to have the bootloader unlocked. Now as far as the carrier/sim lock, either version, Verizon or Google, they come unlocked and. I'm pretty sure they can't be relocked. I believe they would just blacklist the device.

ice711 said:
The op is talking about bootloader being unlocked and your talking about the carrier/sim lock... Verizon pixels that were on a certain firmware were able to have their bootloader unlocked, and then it was patched. So pretty much all Verizon pixel 2 are not able to have the bootloader unlocked. Pixels straight from Google are able to have the bootloader unlocked. Now as far as the carrier/sim lock, either version, Verizon or Google, they come unlocked and. I'm pretty sure they can't be relocked. I believe they would just blacklist the device.
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No, I am talking about both. I only mentioned to be aware that the device may be listed as unlocked due to not having carrier restrictions, but might still be a "Verizon Edition" with a non unlockable bootloader.

Keithn said:
As long as it actually was through Google and not a Verizon one you will be fine. Make sure it's not just carrier unlocked, since the Verizon ones will still be considered unlocked due to being able to use it on other carriers.
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Click to collapse
Keithn said:
No, I am talking about both. I only mentioned to be aware that the device may be listed as unlocked due to not having carrier restrictions, but might still be a "Verizon Edition" with a non unlockable bootloader.
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Click to collapse
Ahh gotcha. Sorry didn't get that when I read it the first time. When you put it this way, I now get what you were saying. Good advise! :good: :good:

Unlocked phone - flashing firmware. Will I lose/keep the unlock code?

Hi, I have a problem with my note 20 ultra and I would like to know precise info because is very important. I live in Italy, and I buy a note 20 ultra sm-n986u in the USA to get the snapdragon variant, which is much better of the version selled here in Europe. The phone was At&t locked, but the seller give me a code to unlock it to insert my italian sim. All is working well, except the fact that the phone never recieve updates due to the fact that I'm not in the USA. So I need to flash a new firmware with odin. So this is the problem:
1) Should I flash an n986u firmware (with At&t bloatware)? In this case I will lose my unlock code?
2) Can I flash a n986u1 firmware to de-brand the phone from At&t? In this case I will lose my unlock code?
3) If I lose my unlock code, will the same code work again?
I searched in theese forum an answer, but no one can give me a precise information, only hypothesis. I think it is a very difficoult argument, but it's very important to me. Can someone help me? Thanks.

Flash it with U1 firmware and it will do auto update. you won't lose the unlock.

randy_c said:
Flash it with U1 firmware and it will do auto update. you won't lose the unlock.
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Click to collapse
Are you 100% sure about that? I will remove At&t limitations and bloatware and keep my unlock code (no need to reinsert it)?

Lol I have att unlock phone for the last several years and did it all the time

randy_c said:
Lol I have att unlock phone for the last several years and did it all the time
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Click to collapse
So basically unlocked phones are brand phones (att, spring, verizon ecc) in which someone already insert the code? And it stays forever?

FedeAle said:
So basically unlocked phones are brand phones (att, spring, verizon ecc) in which someone already insert the code? And it stays forever?
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Yes at&t phone

randy_c said:
Yes at&t phone
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Click to collapse
Ok thanks! Then I will flash U1 firmware if I it keep unlocked. Tell me, does in USA companies uses 4g+? My note stays only on "4G LTE", while my old phone used to stay with "4g+" network.

OnePlus 7 pro t mobile unlocked international firmware install

Hi I will be ordering a one plus 7 pro
t-mobile unlocked and hate the t-mobile firmware so I want to install the international firmware and was wondering if doing so would remove the unlock from the phone making the phone locked to t-mobile

Migbar said:
Hi I will be ordering a one plus 7 pro
t-mobile unlocked and hate the t-mobile firmware so I want to install the international firmware and was wondering if doing so would remove the unlock from the phone making the phone locked to t-mobile
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Click to collapse
What is it about the T-Mobile firmware that you hate? IIRC the only difference is international enables dual sim

weakNPCdotCom said:
What is it about the T-Mobile firmware that you hate? IIRC the only difference is international enables dual sim
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I just hate the boot logo, bloatware and I heard the international firmware runs alot smoother plus gets updates quicker

Are you asking if the bootloader would become re-locked, or if the SIM would become carrier locked? Are both currently unlocked?

Once you are carrier unlocked you are always carrier unlocked. But flashing international wont make you carrier unlocked. You have to have someone on the T-Mobile side do that for you.

greyblue9 said:
Are you asking if the bootloader would become re-locked, or if the SIM would become carrier locked? Are both currently unlocked?
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I'm ordering a tmobile unlocked oneplus 7 pro from Amazon and was wondering if I flash the international firmware could the sim carrier relock

weakNPCdotCom said:
Once you are carrier unlocked you are always carrier unlocked. But flashing international wont make you carrier unlocked. You have to have someone on the T-Mobile side do that for you.
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Click to collapse
So would the Amazon renewed oneplus 7 pro tmobile gsm unlocked be permanently carrier unlocked?

MSM tool will not relock the sim. The lock is in the efs. And this is not flashed by MSM.so you are good to go. But before flashing ,if you are scared it will lock, you can use qfil or edl.py with the firehose programmer elf .and make a backup of modemst1 and modemst2. With these 2 copyed in the unlocked state ,u will be ok. I have locked and unlocked the sim many times for testing by having backups of locked modemst1 and 2 and unlocked. U can go back and forth all u like.alway back these up ,they will only work for your device. With the same HW I'd.

Question Xfinity model that google says is unlocked

I have a pixel6a from xfinity the regulatory label says model GX7AS. I used the Google repair website and checked the imei and it tells me my pixel6a is an unlocked version. Yet oem unlock is still grayed out and if I try a diffrent sim it doesn't work either. Because it's an unlocked model shouldn't I be able to unlock the bootloader?

TerribleT said:
I have a pixel6a from xfinity the regulatory label says model GX7AS. I used the Google repair website and checked the imei and it tells me my pixel6a is an unlocked version. Yet oem unlock is still grayed out and if I try a diffrent sim it doesn't work either. Because it's an unlocked model shouldn't I be able to unlock the bootloader?
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Click to collapse
Most of the time, "unlocked" just means it can be used on any network and has nothing to do with the bootloader unlock. If you're not able to use it with another SIM, I believe you'd need to contact the original carrier (XFinity) and determine if it's carrier locked. They should be able to unlock it for you, or at least tell you why they can't.
I'm not sure whether they can help with the bootloader lock, though. Some variants are not bootloader unlockable.

Yeah idk google told me it's unlocked and I should be able to use any sim but yet I can't it just confuses me like there should be a work around or something. If I got a phone from say tmobile it wouldn't be an unlocked model it would be carrier branded but xfinity pixel is an unlocked model no carrier brand but still locked to xfinity
V0latyle said:
Most of the time, "unlocked" just means it can be used on any network and has nothing to do with the bootloader unlock. If you're not able to use it with another SIM, I believe you'd need to contact the original carrier (XFinity) and determine if it's carrier locked. They should be able to unlock it for you, or at least tell you why they can't.
I'm not sure whether they can help with the bootloader lock, though. Some variants are not bootloader unlockable.
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Click to collapse

TerribleT said:
Yeah idk google told me it's unlocked and I should be able to use any sim but yet I can't it just confuses me like there should be a work around or something. If I got a phone from say tmobile it wouldn't be an unlocked model it would be carrier branded but xfinity pixel is an unlocked model no carrier brand but still locked to xfinity
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Click to collapse
Google doesn't control carrier locking, the carrier does. You need to contact XFinity regarding using it on a different network.

V0latyle said:
Google doesn't control carrier locking, the carrier does. You need to contact XFinity regarding using it on a different network.
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Ok interestingly I factory reset the phone put a tmobile sim in and it works no more this device locked to xfinity but unfortunately oem still grayed out
Edit nvm connected to wifi then it said incompatible wonder if I had an active sim if it connect to network and bypass.

TerribleT said:
Ok interestingly I factory reset the phone put a tmobile sim in and it works no more this device locked to xfinity but unfortunately oem still grayed out
Edit nvm connected to wifi then it said incompatible wonder if I had an active sim if it connect to network and bypass.
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https://www.xfinity.com/mobile/support/article/eligible-to-unlock-phone