First, your KM5 sexually identifies as a La Potato. Use google to find Linux images. Those which rely on EMMC won't work.

Secondly, after you flash your firmware to an SD card; You will need to reflash the bootloader as the one that's used by La Potato doesn't have the correct DDR settings (RAM settings essentially)

You need to use the km5.uboot file and issue the following dd commands:

dd if=km5.UBOOT conv=fsync seek=1 skip=1 bs=512 of=/dev/mmcblk0
dd if=km5.UBOOT conv=fsync bs=1 count=442 of=/dev/mmcblk0

Where /dev/mmcblk0 can be any block device, as long as it's not a partition.