Libre Computer AML-S905X-CC eMMC Flashing Steps from Linux with pyamlboot

And until it is default in every image, always after an eMMC flash:

echo "boot_targets=usb mmc1 mmc0" > /boot/efi/boot.ini
echo "boot_targets=usb mmc1 mmc0" > /media/pi/bootfs/boot.ini

To make it much easier to recover from a bad eMMC system.