Huawei Mate 9 MHA-L29 EMUI9 stock firmware can be downloaded for Asian variants.  The firmware version is 159. This update is only applicable to phones with cust version C636. This firmware is based on Android 9 and runs EMUI9 on top. This is official stock firmware from Huawei and can be installed by following the official method. You can either use sd card/OTG to install it or any 3rd party tool can be used. This firmware can be helpful in unbricking your phone.

Huawei Mate 9 Firmware Details:

• Android Version: 9.0
• EMUI Version: EMUI 9
• Build Number:MHA-L29 9.0.1.159(C636E6R1P8T8)
• Supported Model: MHA-L29C636 (Asia Pacific)
• Update Type: Official Stock Firmware
• Download Link: Click Here
• Password=ministryofsolutions.com MHAL29

Installation Guide:

• Backup all important data from the phone
• Charge the battery up to 60%
• Get a micro SD card with 6GB of free space
• Extract the downloaded firmware zip file (password=ministryofsolutions.com MHAL29)
• Then copy the dload folder to your SD card
• Then power off the phone and disconnect from pc. Hold volume up, volume down, and power, keep holding until the update starts.