Mate 9 Lite keeps restarting after a few seconds of boot

[SoushiS]

Hi, I have that problem of the title. What can it be?
It have TWRP and I did a rollback from Nougat to Marshmallow (Current Build BLL-L23C900B120-log) and after the rollback the problem persists, can't even charge my phone because it automatically boot and well, I tried with a lot of roms with C605 and nothing works. I performed a rollback because after I updated it back then it's build was NDR90M test key and it didn't let me open any banking app because of security reasons. Any solution? Thanks in advance.

Sorry if this is not the right forum. I understand that Huawei Mate 9 Lite is the same as Huawei Honor 6X.

 

[MauriJ2001]

Pls don't flash again B380 or any firmware without the data update.app or you may see the NDRM90-TEST keys trust me next time flash B342

Ok there is still a chance to get working again your device

You will need potatonv (if you got the bootloader locked as user not fblock)

B120log zip and B342 Update and Data update

This TWRP

And Huawei firmware extractor

First recover the phone

I don't know if you really had the bootloader unlocked if you don't you need to unlock it using potatonv with kirin 65x (A) the test point of BLL-L23 is located near the fingerprint conector (right of them) short it when connect your phone to get the EDL and start the potatonv also save your new bootloader unlock code and do the OEM unlock

From the B120 update.app open the Huawei update extractor and extract the recovery and recovery2 images

Put the phone in fastboot mode (put USB and press vol -)

And flash

Fastboot flash recovery recovery.img

Fastboot flash recovery2 recovery2.img

Now take a SD card and make the dload folder and copy the b120 update.app here

Put the phone in dload using the 3 button combo (pwr vol - +) and the update should be installed now

If the process is correct your device will boot as normal with android 6.0 B120Log

To correctly update now the bootloader needs to be still unlocked

Flash the TWRP 3.0.3.0 (newers version directly don't boot)

Copy the B342 zip and this OEM info (not the update.app) to the micro SD (THE INTERNAL MEMORY IS NOT AVAILABLE DURING THIS PROCESS) flash first the OEM info reunlock the bootloader using the fastboot OEM unlock next flash the B342 zip

After that reboot and wait until the system boots complete the device oobe and in the phone info you will still get NDRM90-TEST keys

To fix that you need the B342 Data zip delete in the SD CARD the B120 update.app and replace with the B342 Data update.app

Do again the dload combo and let the phone flash the cust and other info if the process is correct you device info will show the correct compilation instead of NDRM90-TEST keys and safety net should work now (Device certificated)