Another question is about TV boxes with Rockchip RK3318 not being able to boot directly from the SD card when Android is installed.
This sounds like a bootloader incompatibility issue, if you have a BSP Android on eMMC then booting to sdcard with a LE mainline image might not work. If you've got a recovery image or don't mind losing Android, you can try wiping the eMMC and seeing if LE will boot then.