The Galaxy A20's bootloader has a bug where it refuses to load boot/recovery images that don't contain the SignerVer02
magic and an AVB Footer at the end of the partition with the image's size. This results in the "SECURE CHECK FAIL" screen that we all know and love.
- Download the Python script of this repository.
- Run
python fix_bootable_image.py boot.img fixed.img
(replace boot.img with the boot or recovery image you want to fix) - Flash the
fixed.img
image through Heimdall - Done!