[Huawei P20 Pro Guides, News, & Discussion] listerd:
P20 Bootloop after region and firmware update (CLT-AL00 -> CLT-L29)

Hi,

I've followed the funkyhuawei instructions unlocking my P20 Pro, and using the eRecovery method (change DNS settings etc) for Europe Region P20 Pro and firmware CLT-L29C432). All seemed to work fine with the firmware download until the very end when a message came up with 'authentication failure'.

The P20 was unable to boot after the firmware download.

I've tried just about everything, - cleared cache, data, attempted eRecovery again (it doesn't work), but now it is in a bootloop mode.

After the Huawei screen I am presented with 3 options:

1) Press power key to conitnue

2) Press volume up key up to 3 seconds to enter recovery

3) Your device will continue to boot 5 seconds later

If I hold down the volume up key and disconnect the power/USB cable at the point of reboot I can boot into TWRP recovery. Otherwise the recovery just boots back to the same page with the 3 options.

Occassionally I can get into fastboot which tells me the following:

>./fastboot getvar vendorcountry

vendorcountry: hw/eu

> ./fastboot oem get-build-number

(bootloader) :CLT-AL00 8.1.0.111(C00)

> ./fastboot getvar rescue_enter_recovery

getvar:rescue_enter_recovery FAILED (remote: FAIL:need all image flashed!)

> ./fastboot oem oeminforead-SYSTEM_VERSION

(bootloader) :CLT-AL00 8.1.0.111(C00)

I am familiar with adb and can push firmware onto the P20 manually.

I have now tried HuRUpdater (v4) with firmware CLT-L09 C432 - Build 9.0.0. (from androidsage) If I try to install this firmware using HuRUpdate the script proceeds but returns error messages 'Failed to mount /cust, /odm, /product'.

Help please (I am fully paid up).

[SOLVED:

After much messing around and trial and error what seemed to work was:

1) The FunkyHuawei (fh) left the phone wih a version of TWRP that was unable to fix the file partitions problem so the "TWRP - WIPE - ADVANCED - repair " was unavailable.

2) I reinstalled TWRP (tutorial here: https://www.the***********.com/install-twrp-recovery-root-huawei-p20-pro/)

3) Go to WIPE-ADVANCED and select partition (/cust). Select repair. Note existing file structure, chose another one, repair, then return to existing file structure.

4) Select partition (/product). Select repair. Note existing file structure, chose another one, repair, then return to existing file structure. (/odm was left as is, which I understand is used following init procedure)

5) Then followed this tutorial for Firmware Download: https://xdaforums.com/huawei-p20-pro/development/huawei-p20-pro-charlotte-l29c432b131-8-t3809964

For the tutorial I used the FirrmwareFinder tool to find my stock firmware:

https://huaweiadvices.com/huawei-firmware-finder-download-latest-stock-firmware/

from which I selected the latest CLT-L29 build, copied the URL, and downloaded to PC. Then renamed according to guidance in tutorial and used the FlashTool contained in the tutorial.

Working status from Fastboot is:

>fastboot oem get-product-model CLT-L29

>fastboot getvar vendorcountry vendorcountry: hw/eu

>fastboot oem get-build-number (bootloader) :CLT-L29 8.1.0.157(C432)

>fastboot getvar rescue_enter_recovery getvar:rescue_enter_recovery FAILED (remote: FAIL:need all image flashed!)

>fastboot oem oeminforead-SYSTEM_VERSION (bootloader) :CLT-AL00 8.1.0.111(C00)

Key step seemed to be the reinstallation of TWRP which then enabled the partitioned file structure to be repaired by switching between the different file structures.

So I seem to have been able to change a Chinese device to European

CLT-AL00 device to a European CLT-L29. Fingers crossed.

I'm no expert on this but if anyone wants to contact me I'll try to help - particularly as fh failed to respond to any request for help after taking my money.

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