If you cannot boot to Lakka and you are stuck either on the device splash screen or Lakka flower, or get an error message, first try to replace the dtb.img file with the one suitable for your device from here.
If you want to run Lakka on a device like S905X, you can still flash the S905 image, but you will have to use a different DTB (dtb.img) from here specific to your device.