Armbian OS – Amlogic Boot
Booting off SD/USB problems (Amlogic chipsets)
Once you have completed steps 1 through to 8 of the installation article and tried to Boot Armbian, if this doesn’t work, you will need to remove the SD card/USB stick restart and boot into the Android OS that is installed on the box (or if that’s damaged follow the bricked device recovery procedure).
1) When you are booted in to the Android OS, plug in your newly created Armbian SD card/USB stick to the system.
2) Somewhere in the Android interface (Applications folder or within Settings) you will find a program called Update OR Update & Backup. Open this application.
3) You will be presented with the choice to update OTA (Over the Air) or from a Local File. Select Local and browse to your SD card/USB stick.
4) Select the file called aml_autoscript.zip and confirm the upgrade.
5) Your system will reboot, most likely twice. After which it may either boot into your Android OS or it may start booting into Armbian OS. Its also possible it may just do the reboots and then sit at a splash screen for a while. In short, if its not booting an OS within 3 minutes, give it 2 more minutes, then pull the power and try rebooting (with your SD card/USB stick in).
If your system still isnt booting to the Armbian text based setup (meaning it doesnt boot Armbian off your SD card/USB stick), try again with this process and then double confirm you are using the right DTB files in uEnv.ini and extlinux.conf as detailed here.
To explain what aml_autoscript.zip is doing….. The file is from here. The quick understanding that it tells the boot partition of the box, that it has multi-boot (can boot from any device, internal/external) and sets external devices as being the 1st thing to attempt booting off (which would be your SD card/USB Stick).
If you ever re-flash your Android OS onto the box, you will need to follow the above and re-enable the multi boot.