This guide has been written with visual graphics to help users better understand the whole process.

Disclaimer

• Originally this guide has been posted on XDA forum, and credit goes to real developers who have found this work around.
• Photos has been provided by Mr. Alex from Germany who’s phone was converted successfully with my cooperation.

Lets start

• Alex was running B175 on Chinese mate9 as you can see in following photo.

Huawei Mate 9 MHA-AL00 converted to MHA-l29

Steps to follow

• You need good quality sd card with atleast 8GB free space
• Backup all important data
• Charge battery up to 50%
• Enable OEM unlock in developer options
• Enable USB debugging
• Unlock your bootloader by following THIS GUIDE
• Download TWRP from THIS LINK
• Download Asian (MHA-L29C636) OEM info from THIS LINK
• Download MHA-L29C636B110 firmware from THIS LINK  (password=ministryofsolutions.com)
• Switch off the phone, hold volume down and connect with pc, phone will enter fastboot mode.
• Now go to the “Minimal ADB and Fastboot ” folder in C:/Program Files (You have installed when unlocking bootloader) and copy ” twrp-3.0.2-2-hi3660.img ” to that folder.
• Then open MAF32.exe and type fastboot devices and press enter,  if it shows your device serial number, it means the connection is successful.
• Now type ” Fastboot flash recovery twrp-3.0.2-2-hi3660.img ” and press enter. if it shows Ok: finished …
• Then disconnect the phone from the PC and reboot to twrp recovery (Power + Volume up) keep them holding, or switch off and hold the volume up key and connect with pc.
• The following screen will be presented on your phone screen, Don’t press any button just swipe the blue bar.

Huawei Mate 9 TWRP

• On the next screen, you will see the TWRP menu, tap on Wipe then press format data, type yes, and wipe to format data.
• 
• Then go back to the main menu again, and tap on the Backup button, you will see all partitions, only select oeminfo and then swipe to make a backup.

backup oeminfo

• If backup is successful you will see the path where this backup is being saved, normally it is inside TWRP >Backups>serial number>your build number. as you can see in following image.

oeminfo backup

• Now reboot to normal mode, if twrp ask to install any app just ignore it. and reboot

• Now copy that oeminfo to safe place, this is backup of the regional file of your phone.
• Now extract the C636oeminfo zip that you have downloaded earlier, and copy all files inside to to your backup folder and replace your original files with the downloaded one.
• Now extract Asian firmware dload.rar file and copy that dload folder to sd card,
• Download update data zip from THIS LINK
• Now switch your phone off and boot to TWRP recovery again, swipe on 1st screen, then tap on the Restore button, there will be only one backup , select it and swipe to restore.
• Now turn off phone, disconnect from PC. and hold 3 buttons (volume up, volume down, power) and it should start installation of Asian firmware.

Huawei Mate 9 Firmware installation

• Once finished, again enable OEM unlock, unlock bootloader again, enable USB debugging, and install TWRP recovery, as you did at start.
• Then tap install and select zip file ” update_full_hw_spcseas.zip” and swipe to flash.

• You will get error 7 at the end, as shown in image below, but don’t worry.

• Then turn off the phone again, and use the 3 button method to install Asian firmware again. After installation, your bootloader will lock again and you will not get any warning at boot.
• Then go in setting and do a factory reset.

• Once reset finish, boot phone to normal mode, and check build number, voila you will have MHA-L29C636B110. as you can see in the image below

Huawei Mate 9 convert to MHA-L29

And after that user started receiving OTA one by one. as you can see in image below.

Huawei Mate 9 MHA-L20C636B158