I have read around but am struggling to fully understand the significance of the OEM unlock option in developer settings and how/if it relates to FRP.
I have read this article which only goes some way to filling the gaps in my understanding. So I have a few questions and would be grateful for any answers.
1/ OEM unlock.
My understanding is that this should be enabled when the goal is to flash a custom binary (e.g. TWRP) to root the phone. Without this enabled attempting to flash a custom binary via odin will fail. Is this correct?
2/ Flashing stock FW to recover device
In the article linked to above it suggests that if you have an OTA update fail, without having OEM unlock enabled you are stuffed if you wish to recover your device by flashing stock factory fw via odin. Having followed this thread with interest regarding the flashing of stock fw it does not state that you need OEM unlock enabled (no custom binaries are being flashed). So if you are unlucky enough to have an OTA fail do you need OEM unlocked in order to flash a stock fw via odin to recover the device? Surely not???
3/ Relationship between OEM unlock and FRP
FRP requires you to enter your google password to unlock a device after a factory reset. I get this. And you can avoid this by removing your google account from the phone before executing the factory reset. So what is the relationship between OEM unlock and FRP? Is it that if you have OEM unlock enabled you can flash a custom binary (recovery and/or ROM) to then get around the FRP? I'm guessing though. I just don't understand the point. If it's my device I know my google account details so how does having OEM unlock enabled help after a factory reset.
My questions stem from the article I have linked to above which for me raises more questions than it answers. I found myself enabling OEM unlock last night "just in case" but I'm not fully sure what options I've given myself by doing this because as it stands I don't intend to root the phone.
What will happen if I relock bootloader .. because I hate the pop up "your device has been unlocked .." while it boots.. does after relocking bootloader stops twrp to work ?
dhenewar said:
What will happen if I relock bootloader .. because I hate the pop up "your device has been unlocked .." while it boots.. does after relocking bootloader stops twrp to work ?
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If you relock your bootloader with TWRP or anything else non stock, you'll likely boot loop until you unlock again. It's likely you'll trip the verification checks -performed by a locked bootloader - with TWRP, which means you need to be fully stock for a successful locked bootloader. If you've not enabled OEM unlocking in developers options if you locked, then you'll have major issues as you can't then unlock.
If you want to, you can flash a custom logo.bin (plenty of links in the Mods section) which will hide the warning, won't shorten the delay but it'll be nicer to look at.
echo92 said:
If you relock your bootloader with TWRP or anything else non stock, you'll likely boot loop until you unlock again. It's likely you'll trip the verification checks -performed by a locked bootloader - with TWRP, which means you need to be fully stock for a successful locked bootloader. If you've not enabled OEM unlocking in developers options if you locked, then you'll have major issues as you can't then unlock.
If you want to, you can flash a custom logo.bin (plenty of links in the Mods section) which will hide the warning, won't shorten the delay but it'll be nicer to look at.
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Ok bro thanks for the info ..will SuperSu be as same as twrp causing bootloop?... luckily I have got stock recovery n firmware .. as u said "If you've not enabled OEM unlocking in developers options if you locked, then you'll have major issues " .. I am having the problem in other device(Samsung Galaxy grand prime G531H .. Cuz of my careless n rush.i forgot to enable oem n then flashed custom rom in Odin .. then it got bricked.. searched alot in internet for solution..also .. i have created post here.. still no solution .. and Now my device is just waste ..gave up on it ... RIP :angel: ..
dhenewar said:
Ok bro thanks for the info ..will SuperSu be as same as twrp causing bootloop?... luckily I have got stock recovery n firmware .. as u said "If you've not enabled OEM unlocking in developers options if you locked, then you'll have major issues " .. I am having the problem in other device(Samsung Galaxy grand prime G531H .. Cuz of my careless n rush.i forgot to enable oem n then flashed custom rom in Odin .. then it got bricked.. searched alot in internet for solution..also .. i have created post here.. still no solution .. and Now my device is just waste ..gave up on it ... RIP :angel: ..
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I think so, a locked bootloader, as I understand it, checks the integrity of your recovery, kernel and system, and if it detects a break in the chain of trust (e.g. if there's a custom modification that changes the signature expected), then as a security measure the device just won't boot/bootloop. SuperSU or any root, custom kernel, or TWRP or even if you've allowed TWRP to make modifications may result in bootloops thus.
Therefore, if you wish to re-lock your device, you'll want to re-flash the stock firmware and then lock. You can only lock your device with the same firmware or newer than the version your device was updated to (including OTA updates). The latest version we have is the June fastboot ROM: https://forum.xda-developers.com/moto-g4-plus/how-to/stock-rom-npjs25-93-14-4-march-1-t3608138 Of course, flashing this will wipe TWRP, root and possibly your data from your device, so back up and keep the backups off your device. Alternatively, you may just wish to flash the custom logo.bin as mentioned previously, which would hide the bootloader warning.
About your Galaxy Grand Prime, ouch - that's a horrible situation to be in; unless there's a potential bootloader exploit, you're caught in the nasty situation where you can't unlock your bootloader (because of the OEM unlock) and because the security's been tripped, won't allow you to boot to get to the OEM unlock Are there any Samsung service centres or repair shops that could help you recover? You could have a look around the Galaxy Grand Prime forum, see if there's anything that could help: https://forum.xda-developers.com/grand-prime
echo92 said:
I think so, a locked bootloader, as I understand it, checks the integrity of your recovery, kernel and system, and if it detects a break in the chain of trust (e.g. if there's a custom modification that changes the signature expected), then as a security measure the device just won't boot/bootloop. SuperSU or any root, custom kernel, or TWRP or even if you've allowed TWRP to make modifications may result in bootloops thus.
Therefore, if you wish to re-lock your device, you'll want to re-flash the stock firmware and then lock. You can only lock your device with the same firmware or newer than the version your device was updated to (including OTA updates). The latest version we have is the June fastboot ROM: https://forum.xda-developers.com/moto-g4-plus/how-to/stock-rom-npjs25-93-14-4-march-1-t3608138 Of course, flashing this will wipe TWRP, root and possibly your data from your device, so back up and keep the backups off your device. Alternatively, you may just wish to flash the custom logo.bin as mentioned previously, which would hide the bootloader warning.
About your Galaxy Grand Prime, ouch - that's a horrible situation to be in; unless there's a potential bootloader exploit, you're caught in the nasty situation where you can't unlock your bootloader (because of the OEM unlock) and because the security's been tripped, won't allow you to boot to get to the OEM unlock Are there any Samsung service centres or repair shops that could help you recover? You could have a look around the Galaxy Grand Prime forum, see if there's anything that could help: https://forum.xda-developers.com/grand-prime
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Thanx bro I will try it out .. yep bro I got it in service center n they told me .. No way of fixing it .. Aahh n that's it ? .well there was option change of hardware price was half of the phone cost ..better to buy new one ?
Hello i have a J7 Sky Pro sm-s727vl popqltetfnvze. In developer options I have the OEM Unlock switch. I have also ran crom service and it says that I can now install custom os. Is it unlocked?
Really no comments
Crom service doesn't work on this phone, that's why the app reports it's already unlocked, the phone's bootloader is locked, but not by crom.
Sent from my SM-S727VL using Tapatalk
When you try to flash anything modified using Odin the "secure check failed" error you see on your phone screen means that the bootloader is locked.
Hello friends,
Need help here. I am willing to buy T-mobile variant of V20. Its on firmware H91010t march security update. I searched all over the forum for the last one hour but could not get the clear cut answer. If this device can be bootloader unlocked. Can I downgrade to any unlockable older version and unlock the bootloader or now its not possible? Any help will be greatly appreciated. Thanks.
Yeah the H918 is bootloader unlockable, however you need to use a root exploit in order to utilize it as there are limited fastboot commands available.
If you're not familiar with Linux though you should wait for the automated version of the exploit to be released so you can make sure you don't mess anything up.
PhantomGamers said:
Yeah the H918 is bootloader unlockable, however you need to use a root exploit in order to utilize it as there are limited fastboot commands available.
If you're not familiar with Linux though you should wait for the automated version of the exploit to be released so you can make sure you don't mess anything up.
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Thanks bro. Please clarify one more thing. It says we must have bootloader unlocked before proceeding this process. So T-mobile varient comes boot loader unlocked?
hellboyborn said:
Thanks bro. Please clarify one more thing. It says we must have bootloader unlocked before proceeding this process. So T-mobile varient comes boot loader unlocked?
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It comes locked, but it can still (and must) use fastboot oem unlock to unlock the bootloader (the reason exploits are needed is because the h918 fastboot can not flash anything). As usual fastboot oem unlock will factory reset the device so make backups.
As far as rolling back, don't rollback too far or youll brick: just roll back to the version explictly named in the lafsploit guide.
you must enable developer mode and turn on usb debugging <~~~~ in about phone section find the Build number and click it 6-7 times to enable the developer mode option. after that follow the fastboot oem unlocked commands, after unlocking the bootloader. if you want to roll back on firmware DO NOT go before H91810p or you will brick your phone, so your options are h91810p ,q ,r,s, or t which your on. follow the lglaf h918 information in the xda forums. go into search and type lglaf h918. hope this helps
For many years now we have tried to unlock the bootloader with devices with CID 11, I want to know if there is already a way to unlock the bootloader and install twrp to install Custom Roms
If your bootloader doesn't come unlocked, with disabled verification, then sorry, you'll never be able to unlock it.
You want custom ROMs, trade your phone with another S5.