Here are the steps: This will remove android from the system entirely USE AT YOUR OWN RISK
1) Get the debian firmware and SD Firmware Tool from here https://en.t-firefly.com/doc/download/page/id/93.html
2) Burn the debian firmware onto a sdcard using update firmware checked in the sdtool. This creates a FAT partition and adds a .img file
3) Boot into recovery and go to fastboot > System Recovery
4) you will get a prompt sd_update and wait till it is done
5) eject the sdcard
6) Now got to https://disk.yandex.ru/d/JXi9c6YUxpn46A and download the .img file and burn it to the sdcard using balena
7) Once done insert the sdcard into a linux machine and open the boot folder
8 ) take the .dtb file and drop it in the /boot/dtb/rockchip folder from here https://fastupload.io/en/NiNDQTV5toCFPA1/file
9) go back to the boot folder > extlinux > extlinux.conf and change the dtb line to devicetree.dtb
10) in the same file change the root device by removing the UUID and replace it with /dev/mmcblk2p6
11) save the file and remove sdcard
12) insert the sdcard back in the x88 pro 20 and it will boot into the debian system username root pass firefly
ENJOY! I assume someone smarter than me will figure out how to boot into the system without the sd card inserted all the time. If you do please post.
If you want to go back to stock android use https://drive.google.com/file/d/14dx01V70W8ONYPMa2kGURuooJ_zZ_Scx/edit and burn onto sdcard using the SDTool above, but this time select SD Boot
