Mi A2 : installing UT over Android One - the bootloader issue

wilfridd · 11 Jun 2021, 16:43

Hi,
I've read all posts related to Mi A2 install before.
I tried to keep this post detailed but as short as possible.
The phone is a Mi A2 Global Version and came with Android One (8.1.0) installed. It seems to be a stock Android without MIUI stuff. The phone is brand "new", no sim lock. I mean it has never been used before.

adb devices -l says : product:jasmine model:Mi_A2 device:jasmine_sprout

I installed several updates to get Android 9, became developer, allowed both OEM unlocking and USB debugging.
I also did : fastboot oem unlock_critical (edit : "fastboot oem unlock" is fine)
Then I did a backup with TWRP : fastboot boot twrp-3.5.2_9-0-jasmine_sprout.img.
And finally selected slot B to install UT

I started UBI 0.8.8 beta to install UT. UBI identified the phone as "jasmin" and I had to do a manual install with rc channel + wipe + bootstrap : 1st step in fastboot, 2nd in recovery (Halium 9). UBI said Success! The phone reboots automatically to finish the installation and reboots again to the initial setup...
Ofc at reboot the message is displayed "The bootloader is unlocked and software cannot be verified...". I noticed the Android One boot logo is still there with the "Unlocked" sign, it should not a be problem but it shows that the bootloader is still the "Android One".

I restarted to fastboot mode to lock the bootloader again : fastboot oem lock.
But the phone refuses to start and displays "Your device is corrupt. It can't be trusted and will not boot"
Seems that it can boot UT only with bootloader unlocked or obviously I missed some important step ?
Thanks in advance for you suggestions and help!

MrT10001 · 31 Oct 2021, 17:13

You have to OEM unlock the device as well, a further security feature from Xiaomi. In developer options there is an OEM unlock button that I think you have found. This gave me some extra steps I had to follow when I switched it over. (learning curve from my first attempt with an Xiaomi phone - Redmi Note 7. If I remember correctly I may have had to format the data and system partition to EXT4. If you can boot UT it is all good, if you relock the bootloader it will try and boot into Android.

wilfridd · 31 Oct 2021, 17:40

@mrt10001 Thanks for your reply!
Yes, I have found the OEM unlock. BTW, the miflash tool shows the bootloader status
(bootloader) Verity mode: true
(bootloader) Device unlocked: true
(bootloader) Device critical unlocked: false
--> this one may cause the issue? not sure...
(bootloader) Charger screen enabled: false

You mean that you had to leave your bootloder unlocked on your phone?

Keneda · 31 Oct 2021, 17:47

@nauvpp said in Mi A2 : installing UT over Android One - the bootloader issue:

I restarted to fastboot mode to lock the bootloader again : fastboot oem lock.

Sorry i don't have your phone but that was a bad move.
Try to unlock again.

Ubports obviously don't have any key from xiaomi or google to "verify" the boot process of uTouch.

wilfridd · 1 Nov 2021, 06:11

@keneda Thank you.
I unlock it again...that is the only way to boot UT but the warning message at boot is not really nice.

I agree with you regarding the "key".
I own a Meizu MX4/Pro5 and Nexus5, they must have their custom bootloader so it trusts UT.
I will search XDA for a possible solution...

Lakotaubp · 1 Nov 2021, 06:11

@nauvpp That boot message appears on a number of devices OP3 and OP5 that I have for instaance. Please just ignore it, your bootloader needs to be unlocked for UT to work.

nero355 · 1 Nov 2021, 15:57

Also :

NEVER LOCK the Bootloader after UNLOCKING it on any phone!

It will leave you with a BRICK!

And in most cases it means contacting shady people via shady ways to get your phone working again by letting someone access it via the EDL Mode which is hidden on many phones these days!

wilfridd · 2 Nov 2021, 22:05

@nero355 Hi, I wouldn't be so categorical about bootloader locking : On the N5 hammerhead, I've locked the bootloader again and... it boots OK so does the update (devel channel). Interesting fact : fastboot screen says:

Prd name - hammerhead
HW version - rev.11
bootloader version - HHZ12h
...
secure boot - enabled
lock stat - locked
Again, I'm not an expert, but it seems to me that N5 benefits a dedicated/custom bootloader/recovery mode that trusts UT and let it boot happily :grinning_face_with_big_eyes:
BTW the UBports Recovery is awesome ! Hats off to Devs!

AppLee · 3 Nov 2021, 08:45

@nauvpp
The N5 is not a Halium port.
This is a custom image initiated by canonical so maybe they put the time and effort into this possibility.
Most UT compatible devices are Halium based and won't work with a locked bootloader.

jonlockwood17 · 5 Nov 2021, 14:22

It seems to be the nature of the beast. the annoying boot loader screen isn't a huge deal, but it does beg the question, how secure is the OS? Does this mean google has a back door?

Lakotaubp · 6 Nov 2021, 06:07

@jonlockwood17 Have a read of this thread https://forums.ubports.com/topic/6941/getting-rid-of-the-warning-at-boot as to why.

nero355 · 6 Nov 2021, 14:35

@jonlockwood17 said in Mi A2 : installing UT over Android One - the bootloader issue:

It seems to be the nature of the beast. the annoying boot loader screen isn't a huge deal, but it does beg the question, how secure is the OS? Does this mean google has a back door?

I wouldn't worry a lot about that : Google and Microsoft forced a lot of their Secure Boot crap on us which 99,99% of us totally do not need!