How To Guide Unlock bootloader and root A125U u3

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Wish39

Senior Member
Jan 13, 2015
201
55
God bless you , I can just downgrade like that with Odin? I thought Samsung could only move up in binary number when you flash, never down ? But if so that's awesome. *Update* yeah that didn't work lol still won't go into brom and still no oem unlock toggle... It took the firmware tho so there's that
Are you trying to use mtkclient with Windows? It might not be working because it doesn't really play nice with Windows, it works fine when running it on a Ubuntu or Debian distro.
 
Are you trying to use mtkclient with Windows? It might not be working because it doesn't really play nice with Windows, it works fine when running it on a Ubuntu or Debian distro.
I tried it on windows and Linux both and then again in windows and Linux running in virtual box and then tried to test point into brom for like 4 hours and nothing lol I also tried 4 different mediatek boot mode tools it's looking hopeless
 

Wish39

Senior Member
Jan 13, 2015
201
55
I tried it on windows and Linux both and then again in windows and Linux running in virtual box and then tried to test point into brom for like 4 hours and nothing lol I also tried 4 different mediatek boot mode tools it's looking hopeless
Hmmm, before updating I was able to get my A21 to BROM mode using a Debian distro by first running a command in mtkclient, then plugging in the powered off phone and letting mtkclient crash the preloader in order to get to BROM mode. After that then the command will execute, ex: "python mtk printgpt" would get me the partition layout of the phone. I was able to make a full dump of the phone and even ran the bootloader unlock command on it, which didn't unlock the bootloader unfortunately lol.
 

gokurockx9

New member
Sep 9, 2018
3
0
You write the BL_A125.tar, disconnect the battery and unlock the booloader, after this it enters without problems and is deleted.
If it doesn't, disconnect battery and force enter recovery with volume up and power, do a factory reset
For somebody who has been out of the rooting game for years, can you explain to me this BROM mode?? I have to remove the back of these nonremovable battery phones? I remember when the backs and batteries of Androids could be removed like old radios. Idk how to remove the back of my Galaxy A12 (A125U). Can you point me to a guide as to how to do the BROM mode? I've never heard of it
 

gokurockx9

New member
Sep 9, 2018
3
0
I'm assuming you guys are on the newest firmware. Samsung patched up BROM mode in the February 2022 security update, that's why mtkclient or in some cases testpoint will not work, my A21 does not enter BROM anymore as well after that update. Try downgrading to this firmware: A125USQS3BVA2, that's the January 2022 security patch firmware and is not patched up.
Do you mean A21 or A12? please clarify what model phone you're referring to.
 

gokurockx9

New member
Sep 9, 2018
3
0
Requirements:
-Tested working on firmware A125USQS3BVA2
-A MTK bootloader unlocking tool, tested working with UnlockTool
-This is for A125U on binary 3 ONLY

Special thanks to @Boster27 for translate guide and test method


Steps:

1- Boot into Download Mode (vol+ & vol- & pwr) and flash this custom BL file BL_A125.tar with ODIN patched using the BL button. The device will reboot to an error screen, this is normal.

2- Boot into BROM mode using Test Points (picture attached, needs light dissasembly). Using UnlockTool or your MTK tool of choice, head to the Samsung section and select A125, then on the BROM tab, choose Unlock Bootloader.
After this the device should reboot into recovery and perform a factory reset automatically. In case it doesn't, go into recovery manually (vol+ & pwr) and perform a factory reset. After this the device should boot normally.

3- Once the setup process is complete, connect to Wifi and enable Developer Options to confirm that OEM Unlock is enabled and unlocked. Install the latest version of Magisk Manager and use it to patch the AP file for the corresponding firmware.

4- Boot into Download Mode, make sure the AutoReboot option is unchecked in ODIN, and flash the magisk_patched.tar AP file, and the stock CP, CSC and USERDATA files. Then manually boot into recovery and perform a factory reset. After this the device should boot normally.

5- Once the setup process is complete again, connect to Wifi and enable Developer Options to confirm that OEM Unlock is still enabled and unlocked. Install the latest Magisk app and launch the app.
It should show a dialog asking for additional setup. Let it do its job and the app will automatically reboot your device.

And done! Phone is rooted on binary 3!
You didn't think to mention or refer to a guide on how to boot into BROM mode? Which involves opening the back and unscrewing ridiculously small screws? Why does no one mention these things? Root guides are **** compared to 2012 root guides and people should feel bad for failing to specify detailed instructions.
 

mfeliu07

Member
Mar 17, 2009
37
1
Habana
For somebody who has been out of the rooting game for years, can you explain to me this BROM mode?? I have to remove the back of these nonremovable battery phones? I remember when the backs and batteries of Androids could be removed like old radios. Idk how to remove the back of my Galaxy A12 (A125U). Can you point me to a guide as to how to do the BROM mode? I've never heard of it
 
In reference to the SM-A125U on A125USQS3BVA2 , after spending several days and every piece of unlocking /mtk / Samsung tool known to mankind I think it's safe to say that this phone can NOT be downgraded using combination file, test point, or any other method I've found online at the moment but I did find this software (which I have no idea about whether it's safe or not, but I'm about to try it so I will let you all know) but the information it has listed might be useful to someone that understands it better than me , it goes into detail about what changes were made and why we can't unlock with other methods and how to do it a new way , So I will try it, but if anyone else understands the instructions, I'm more than glad to help if you need it with testing , etc.



**Update **.. even though this tool works and says it's for our specific device and even has dedicated buttons for it ...for some reason I can't get out of brom mode now , phone is completely bricked won't boot at all and won't respond to anything other than just showing up as brom mode. Do NOT use this unless you know what you're doing .
 

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Wish39

Senior Member
Jan 13, 2015
201
55
In reference to the SM-A125U on A125USQS3BVA2 , after spending several days and every piece of unlocking /mtk / Samsung tool known to mankind I think it's safe to say that this phone can NOT be downgraded using combination file, test point, or any other method I've found online at the moment but I did find this software (which I have no idea about whether it's safe or not, but I'm about to try it so I will let you all know) but the information it has listed might be useful to someone that understands it better than me , it goes into detail about what changes were made and why we can't unlock with other methods and how to do it a new way , So I will try it, but if anyone else understands the instructions, I'm more than glad to help if you need it with testing , etc.



**Update **.. even though this tool works and says it's for our specific device and even has dedicated buttons for it ...for some reason I can't get out of brom mode now , phone is completely bricked won't boot at all and won't respond to anything other than just showing up as brom mode. Do NOT use this unless you know what you're doing .
Flashing the preloader back to the phone may fix the brick, give me some time to figure out a process
 
Flashing the preloader back to the phone may fix the brick, give me some time to figure out a process
thats exactly what the issue is lol when i was flashing things it wanted a preloader and theres 2 different ones inside the stock firmware one is like titan rat and then theres another one and i guess i flashed the wrong one but i have no idea how to flash a preloader being that it cant even be detected , what i really dont understand is am i using sp flash tool to flash since its mediatek or am i using odin...
 
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thats exactly what the issue is lol when i was flashing things it wanted a preloader and theres 2 different ones inside the stock firmware one is like titan rat and then theres another one and i guess i flashed the wrong one but i have no idea how to flash a preloader being that it cant even be detected , what i really dont understand is am i using sp flash tool to flash since its mediatek or am i using odin...
To my understanding there is only one preloader.
 
To my understanding there is only one preloader.
contained within the official firmware there is preloader.img and also preloader_k65v1_64_bsp_titan_rat.bin im assuming i flashed the wrong one but i cant remember which ..i cant get sp flash tool to work at all no matter what i try even tho my drivers are right also so i have no clue at this point lol. ***Edit*** finally got it fixed it, just needed the right preloader and it's working again but back to square one with the root lol
 
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contained within the official firmware there is preloader.img and also preloader_k65v1_64_bsp_titan_rat.bin im assuming i flashed the wrong one but i cant remember which ..i cant get sp flash tool to work at all no matter what i try even tho my drivers are right also so i have no clue at this point lol. ***Edit*** finally got it fixed it, just needed the right preloader and it's working again but back to square one with the root lol
What is the right preloader??? Please link it to me this phone been dead for at least 2 weeks
 

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  • 2
    Requirements:
    -Tested working on firmware A125USQS3BVA2
    -A MTK bootloader unlocking tool, tested working with UnlockTool
    -This is for A125U on binary 3 ONLY

    Special thanks to @Boster27 for translate guide and test method


    Steps:

    1- Boot into Download Mode (vol+ & vol- & pwr) and flash this custom BL file BL_A125.tar with ODIN patched using the BL button. The device will reboot to an error screen, this is normal.

    2- Boot into BROM mode using Test Points (picture attached, needs light dissasembly). Using UnlockTool or your MTK tool of choice, head to the Samsung section and select A125, then on the BROM tab, choose Unlock Bootloader.
    After this the device should reboot into recovery and perform a factory reset automatically. In case it doesn't, go into recovery manually (vol+ & pwr) and perform a factory reset. After this the device should boot normally.

    3- Once the setup process is complete, connect to Wifi and enable Developer Options to confirm that OEM Unlock is enabled and unlocked. Install the latest version of Magisk Manager and use it to patch the AP file for the corresponding firmware.

    4- Boot into Download Mode, make sure the AutoReboot option is unchecked in ODIN, and flash the magisk_patched.tar AP file, and the stock CP, CSC and USERDATA files. Then manually boot into recovery and perform a factory reset. After this the device should boot normally.

    5- Once the setup process is complete again, connect to Wifi and enable Developer Options to confirm that OEM Unlock is still enabled and unlocked. Install the latest Magisk app and launch the app.
    It should show a dialog asking for additional setup. Let it do its job and the app will automatically reboot your device.

    And done! Phone is rooted on binary 3!
    1
    I was able to do it, thanks.
    I wrote full firmware, wiped and started from scratch, everything went ok, thanks
    1
    You write the BL_A125.tar, disconnect the battery and unlock the booloader, after this it enters without problems and is deleted.
    If it doesn't, disconnect battery and force enter recovery with volume up and power, do a factory reset
    Thanks for helping. I rooted 4 note 4s and they all finally give out so I am going to try a newer phone
    1
    Do you mean A21 or A12? please clarify what model phone you're referring to.
    I do mean A21 as I own one, it was only sold in the USA and Canada. It has the same CPU as the A12.