Start Armbian external media of appropriate size. If the eMMC there is not a lot of data should be sufficient 16 GB media (backup compression). Open a terminal and execute "sudo dd_backup_x" or "sudo ddbr". Then choose what you need to do (copy or restore) and follow the prompts. The script will automatically create\restore a complete copy of all contents of the internal memory for later recovery or for transfer to new hardware.