MattWestB

@TU-Student I have one little older version of the board and have finding the hardware pins for UART and MASK-ROM and its the same on your. Look on the posted images i haw done before and you is getting all you need. I can also see that your board have being "fixes" hard or software then its have new label over the original so very likely they have flashing one "updated" Android on it before shipping it. I have modded the SD-Card so i can have its mounted inside the box then i need it for running HA and its only having 1/8 G that is OK but not flash for running supervised version and is working very well if not using USB that is crashing and need hard restart for working OK.

@EmilB As long you is having the original u-bootloader on the internal eMMC the device cant boot armbian on external storage. Erasing the eMMC is making the internal ROM in the SOC looking for u-bootloader on the SD-card and you can then booting SD, USB and internal storage from it if doing the config OK. My box was not liking the standard bootloader but i was getting it working then finding one working one and flashing it from MASKROM mode on the eMMC and then i can booting from all connected device also USB if the internal not being OK and can fixing it from CLI.

@remlei OS agent for ARM 32 and supervised select Pi 3 (not 64 bit version) and also need patching the boot parameters for getting the install working OK by faking GRUB settings.