How to factory reset/restore M2U

I need to factory reset BPI-M2U (restore Android on emmc and boot order) to the originally shipped default settings.
Please post URLs If there is any detailed tutorial or instruction on the web for this restoration.

I can only boot from a newly burned SD (using .img file) but I can’t boot/reboot after the 1st boot. (It stops at the below screen)

Please provide URL or necessary steps to factory reset/restore M2U by Armbian or any possible distribution.