Huawei devices are easy to brick by making a single mistake during the manual upgrade, especially when flashing wrong ROM via TWRP recovery or cmd. Probably that’s the reason why you’re reading this tutorial right now.
Great news is that we’re going to help and all you need to do is to follow the tutorial given below.
Unbrick Huawei P9 Lite with unlocked Bootloader
Tutorial Nr. 1
Prerequisites:
• The device should have at least 60% charge left on the battery.
• ADB and Fastboot drivers must be installed on PC.
Warning: Update process will erase device internal storage, so we’ll guide you through the backup process in TWRP recovery menu.
This tutorial is only for Huawei P9 Lite (L21 and L31) model with unlocked Bootloader. If your device Bootloader is locked, please follow the second tutorial below.
You can check Bootloader status by simultaneously pressing Power + Volume Up + Volume down button. 
Tutorial:
1. Using PC download both update.zip and update data full public.zip files depending on your model:
L21
update.zip
update_data_full_public.zip
L31
update.zip
update_data_full_public.zip
2. Upload files into device microSD card.
3. Using PC download TWRP recovery file.
4. Power up Huawei P9 Lite and connect it to PC via USB cable.
5. On PC open cmd window: holding shift key, right click on empty space in folder where twrp.img file is placed and choose Open command window here.
6. In cmd window type:
| adb devices |
You should get a message saying List of devices attached. This confirms that device is properly connected.
7. Next reboot your Huawei P9 Lite into bootloader mode by typing this command:
| adb reboot bootloader |
8. Next, type the following command and hit enter:
| fastboot flash recovery twrp_p9_lite.img |
9. After recovery flashing is complete, type adb reboot recovery and hit enter to reboot Huawei P9 Lite into TWRP recovery.
You can also boot into recovery by simultaneously pressing and holding Power + Volume Up + Volume down button until TWRP menu shows up.
10. Make a current software backup, so you will have a recovery file. Tap on Backup and select all the partitions including System, Data, Boot and Cache. Then swipe to make a backup. 
11. Go back to TWRP recovery menu then choose Wipe, Advanced Wipe and select: Dalvik Cache, System, Cache, Data, Internal Storage.
This will completely format internal storage so we can make a clean install of new OS.
12. Again, go back to main menu and tap on Install 
Select update.zip file and slide to begin flashing.
13. After flashing is complete select update_data_full_public.zip and again slide to flash.
14. Once flashing is complete choose Wipe cache/dalvik and tap on Reboot System. 
First boot might take up to 15 minutes so be patient and do not interrupt the process.
Congratulations! Huawei P9 Lite is unbricked and running Nougat 7.0
Unbrick Huawei P9 Lite with unlocked Bootloader
Tutorial Nr. 2
You should try this tutorial only if the above one didn’t work out.
Prerequisites:
• The device should have at least 60% charge left on the battery.
• ADB and Fastboot drivers must be installed on PC.
Warning: Update process will erase device internal storage, so we’ll guide you through the backup process in TWRP recovery menu.
This tutorial is only for Huawei P9 Lite (L21 and L31) model with unlocked Bootloader. If your device Bootloader is locked, you won’t succeed.
You can check Bootloader status by simultaneously pressing Power + Volume Up + Volume down button.
Tutorial:
1. Using PC download both update.zip and update data full public.zip files depending on your model:
L21
update.zip
update_data_full_public.zip
L31
update.zip
update_data_full_public.zip
2. Extract update.zip file to PC. You’ll find a folder that includes boot.img and system.img files.
3. Upload update_data_full_public.zip file into device microSD card.
4. Using PC download TWRP recovery file.
5. Power up Huawei P9 Lite and connect it to PC via USB cable.
6. On PC open cmd window: holding shift key, right click on empty space in folder where twrp.img file is placed and choose Open command window here.
7. In cmd window type:
| adb devices |
You should get a message saying List of devices attached. This confirms that device is properly connected.
8. Next reboot your Huawei P9 Lite into bootloader mode by typing this command:
| adb reboot bootloader |
9. Next, type the following command and hit enter:
| fastboot flash recovery twrp_p9_lite.img |
10. After recovery flashing is complete, type adb reboot recovery and hit enter to reboot Huawei P9 Lite into TWRP recovery.
You can also boot into recovery by simultaneously pressing and holding Power + Volume Up + Volume down button until TWRP menu shows up.
11. Make a current software backup, so you will have a recovery file. Tap on Backup and select all the partitions including System, Data, Boot and Cache. Then swipe to make a backup.
12. Go back to TWRP recovery menu then choose Wipe, Advanced Wipe and select: Dalvik Cache, System, Cache, Data, Internal Storage.
This will completely format internal storage so we can make a clean install of new OS.
13. In main menu select Reboot and tap on Bootloader.
14. On PC open cmd window: holding shift key, right click on empty space in folder where boot.img and system.img files are extracted and choose Open command window here.
15. In cmd window type:
| fastboot flash boot boot.img |
16. After flashing is done, lets flash system file by typing:
| fastboot flash system system.img |
17. Boot Huawei P9 Lite into recovery by simultaneously pressing and holding Power + Volume Up + Volume down button until TWRP menu shows up.
18. Tap on Install and select update_data_full_public.zip then slide to flash.
19. Once flashing is complete choose Wipe cache/dalvik and tap on Reboot System.
First boot might take up to 15 minutes so be patient and do not interrupt the process.
Congratulations! Huawei P9 Lite is unbricked and running Nougat 7.0
Unbrick Huawei P9 Lite with locked Bootloader
- Download compatible update.zip file for P9 Lite:
– for the VNS-L21C432B381 get this update.zip
– for the VNS-L21C432B380 get this update.zip
– for the VNS-L31C432B381 get this update.zip
– for the VNS-L31C432B380 get this update.zip - Extract downloaded file, make a new folder and name it to dload. Place all the unzipped files in this folder.
- Upload dload folder to microSD card.
- Put microSD card to P9 Lite.
- Turn off the phone.
- Hold Power + Volume Up simultaneously and release them right after boot screen shows up.
- Using volume button go to Wipe data/factory reset section and push Power button to start factory restore.
- After it’s done, turn off the phone.
- Hold Power + Volume Down + Volume Up buttons simultaneously and release them after boot screen shows up.
- Update process should start automatically.
- After system upgrade is done, Huawei P9 Lite will reboot.
That’s it!
