[Huawei P9 ROMs, Kernels, Recoveries, & Other Devel] zgfg:
Ok, so this is a do-it-yourself modifucation of HWOTA method for upgrades (or clean reinstallations) of EVA-L09c432 b39x stock firmwares on the Huawei P9 phone.

You must already have EVA-L09c432 b38x/b39x firmware installed on the phone.

Bootloader must be unlocked and TWRP 3.1.1 must be installed.

You may be upgrading from a rooted b39x but upgrade will make clean install (root lost). Upgrade will also replace TWRP by stock Recovery, but Bootloader will remain unlocked.

Only certain upgrading combinations are allowed, like from b394 to b397 (but not directly to b398). If unsure, upgrade always to the next subsequent build number (like from b397 to b398 and then to b399).

DO IT ALL ON YOUR OWN RISK!

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Download and unzip this HWOTA_EVA-L09c432_template.zip from:

https://mega.nz/#F!JwkVyRya!Rb7OUE0z3PEpXBRxGOM-vQ

Rename the unzipped folder to HWOTA (exactly that name), it must contain:

- empty subfolder FullOTA_MF

- EVA_L09_nocheckrecovery.img

- hwota_update.zip

- and this guide

Do not delete or rename first three, keep the third zipped as is.

From FirmwareFinder download any FullOTA-MF package for EVA-L09c432b39x. Download the following three files and copy them to the FullOTA_MF subfolder:

- update.zip

- update_data_full_public.zip

- update_full_EVA-L09_hw_eu.zip

Keep them zipped and do not rename them.

Copy this complete HWOTA folder (unzipped, with the downloaded three files in the FullOTA_MF subfolder) to the phone.

It must be named HWOTA and must be copied to the main directory (root of file-system, not into any other folder) on the SD card.

Make backup of everything on the phone by using Huawei Backup application on the phone, save the backup to SD card.

Contacts can be also backed-up through Contacts / More / Import/Export / Export to SD card.

Copy DCIM (not needed if you chose to backup Photographies through the Backup application), WhatsApp and any other folder you want to keep from Internal memory to SD card - firmware update will erase Internal memory!

Alternatively, you can backup WhatsApp to your Google Drive.

Similarly backup any other Social Media or Instant Messaging application you may have.

Skype does not need any backup.

Under Settings / Accounts sync all your accounts -and then delete them from the phone.

Remove Fingerprint/PIN/Password protections on the phone!

Make sure that following options are enabled in the Settings / Developer options (to be able to flash from scratch if things go wrong and you brick the phone)

- OEM Unlocking

- Allow ADB debugging in Charge only mode

- ADB debugging

(last two must be enabled in that order, otherwise ADB debugging option will not be saved).

Reboot to TWRP.

You can make Nandroud backup (again for your own safety if things go wrong), but you can not use it to 'restore' e.g. Data partition upon upgrading!

In TWRP, choose Install (ZIP,* from SD card), select to install hwota_update.zip from HWOTA folder on the SD card.

Swipe to Install. It will automatically reboot to the System.

Go to Settings / Advanced settings / Backup and restore and do Factory reset with wipe of Internal storage.

When phone starts rebooting, immediately press and keep pressing Vol+ to boot to eRecovery, and select Wipe Cache Partition.

Reboot to System and configure your phone. Restore everything from Huawei Backup application - except Data for WhatsApp or similar Social Media or Instant Messaging applications!

Copy back from SD card to Internal memory DCIM, WhatsApp or other folders you have previously copied (saved from wiping of Internal memory) to your SD card.

Restore Contacts from SD card through Contacts application (not needed if you backed-up/restored them through Huawei Backup application).

Reboot. Sync your Accounts in Settings.

Run WhatsApp and let it restore from Internal memory (or Google Drive).

Similarly restore any other Instant Messaging or Social Media applications.

Skype will be automatically restored when you enter your credentials.

Configure back your Fingerprint/PIN, etc.

Enjoy your upgrade :)

PS: If you make subsequent upgrades from e.g. b397 to b398 and then to b399, unzip and copy HWOTA folder only once to SD card on the phone.

For the first upgrade, download and copy the frst three corresponding ZIPs to FullOTA_MF subfolder and execute upgrading as above.

For the subsequent upgrade(s), reinstall TWRP and replace content of HWOTA/FullOTA_MF on the SD card by the three new corresponding ZIPs from FirmwareFibder and repeat the upgrade.

Do Factory reset only upon the first and last upgrade.

Restore your applications and stuff only upon the last upgrade.

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E.g., HWOTA_L09c432b399.zip already contains upgrade for EVA-L09c432b399:

https://mega.nz/#F!JwkVyRya!Rb7OUE0z3PEpXBRxGOM-vQ

It must be unzipped, renamed and copied as HWOTA folder to the main directory (root of file-system) on the SD card. The rest goes as above...

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This is a do-it-yourself modification of HWOTA method by [MENTION=6870018]Tecalote[/MENTION]

https://xdaforums.com/showpost.php?p=74913874&postcount=3

which is based on NoCheck Recovery method by [MENTION=4081738]Atarii[/MENTION]

https://xdaforums.com/p9/development/eva-nocheck-recovery-flash-unapproved-t3705125

that was based on Updating to Unapproved OTAs method by [MENTION=4960686]OldDroid[/MENTION]

https://xdaforums.com/honor-8-pro/how-to/oeminfo-c432-t3625886

All credits go to the listed authors :)

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Edit: Removing my downloads from above, use modified (based on above) HWOTA method:

https://xdaforums.com/showpost.php?p=75787156&postcount=3