This guide uses unofficial methods (hacking the bootloader via test-point or paid services). Results are not guaranteed.
Phone will factory reset and reboot. First boot takes 5-10 minutes. How to Unlock Bootloader in HUAWEI P20 Lite phone
). It requires disassembling the phone to short a "test point" on the motherboard while connecting it to a PC. You can find the tool on the PotatoNV GitHub . This guide uses unofficial methods (hacking the bootloader