bootloader unlock not allowed : NO?
from France !
I just want to know if there is a tip for my old xperia s (LT 26i) to change this status ( bootloader unlock not allowed : NO !) to YES then i can unlock my bootloader at the end to install custom rom because there is more and more apps who didn't work at all !
i found old topics in xda (testpoint method, wotan and omnius server but it was only for 2011 smartphones). Now i was wondering if it's possible (if i find one with good status) to flash a TA partition ? In this case maybe you can send me one...
Anyway, i've never told about that when i've bought my phone, so my operator would be agree if you have to fix the phone...
I'm a tech guy with developper abilities so i can follow any procedure
Thanks for answering me because from now no one was able to give me a clear answer
Have a good day ( excuse my french, hope it's understandable ! )
Mr Niederlender
Answer
I have some experience with the Xperia bootloader, having an Xperia SP myself and messing with it.
Not so long ago, I stupidly flashed the simlock.ta file included in an .ftf file in Flashtool, thinking it would resolve my SIM-card reader issues. I've had an unlockable/unlocked bootloader up until that point. Upon booting the phone up again, the bootloader was locked, and the service menu said "Bootloader unlock allowed: NO".
I've tried messing with my TA partition and all kinds of simlock.ta files, but I've figured out with a friend of mine with an SP aswell, the TA seems to have a value, a sort of hash it checks the simlock section of the TA, and if it doesn't match, it activates a lockdown, disabling the SIM-card reading ability, disabling fastboot completely (booting normally to Android when volup + power or adb reboot bootloader). Literally changing the TA file and flashing it back won't work, the phone will be hard-bricked at that point and you'll need to use the testpoint found by taking the device's back apart, a hard-to-find tool to convert your TA backup into a SETool2-workable file and SETool2 to restore a backup of the TA you've made before doing any of the changes. (if you forget the backup, dead device)
Now I have done some research and found that 2011 Xperia devices had in their TAs a "Security Unit" section, which basically holds to-your-device-exclusive numbers that determine whether the TA is truly yours and whether the device boots. I'd assume the same holds true today, or at least for the Xperia SP, and if we could get an Xperia SP TA backup with an unlockable/unlocked bootloader, we could patch this TA file to have our own unique Security Unit inside and possibly have a bootable device with an unlockable bootloader with fastboot back, even if the SIM-card reading is gone.
This is, of course, definitely against what Sony would want us to do, and also not an answer that is a solution, but considering our warranties are over, the device has reached its end of support by Sony, and I've taken the device apart to be able to use its testpoint, I think this "hacky" method is still a theoretical solution.
Hope this helped you understand the situation better, and I'm also hoping there'll be someone that can help us in the future. This is such a great device with a custom ROM (specifically StryFlex Marshmallow is a beast on this device) and I'm hoping I'll one day see it working with it again.
TL;DR: Purely flashing a TA partition of another device hard-bricks the phone, possible (theoretical) workaround to hard-brick by patching the new TA to have our old Security Units section.
Simlock afterall does correspond to bootloader-unlockability, flashing a simlock file activates a sortof "lockdown" to SIM-reading, fastboot and bootloader-unlockability.