
Hold shift + right click to open a command window inside that directory. Navigate to where you downloaded and extracted your TWRP recovery.img. ***Note: the article has a slight error in the commands, starting with Android 8.0 fastboot flash recovery should now be flash recovery_ramdisk otherwise you will get FAILED (remote: partition length get error). Use fastboot to flash recovery (once bootloader is rebooted you should see Phone: Unlocked this confirms your unlocked bootloader) I followed part of this tutorial located at: Upon restarting you'll be greeted with a warning that your device may not be secure anymore and a few options to go to recovery or to boot into your stock rom.

How to extract Huawei firmware and its UPDATE.APP file Once downloaded you will have to extract the UPDATE.APP file from your firmware.The closes firmware I was able to find was MAR-LX3A & Marie-L03A 9.1.0.215(C792E9R1P5). My P30 Lite came with Android 9.1.0.325 (C792E9R1P5) - Model Number MAR-LX3A. You will have to download a copy of the firmware that matches your model number/build number.

Use TWRP to flash unofficial Lineage OS 17.1 Install 'Treble Info.apk' to determine which architecture your phone is (mine was ARM64 A/B system) Use DC-Pheonix / HCU to unlock bootloader (This is a paid service) I was able to unlock my bootloader (not free) on my Huawei P30 Lite MAR-LX3A (C79) then successfully install TWRP and flash an unofficial Lineage OS 17.1 ROM. Xda delete my post so here are the instructions:
