Tested on Zenfone 4 Max ZC520KL X00HD android 7 and 8
Unlock Bootloader + flash twrp
- adb reboot bootloader
- fastboot devices
- echo > key.txt
- fastboot oem get_unlock_key key.txt
- fastboot reboot-bootloader
- fastboot flash recovery recovery.img
- fastboot boot recovery.img
Combination key
- Recover mode : vol down + power
- fastboot mode : vol up + power and then select menu using vol button