LE has always required a formatted target. The installer script uses the "blkid" command to identify potential install targets and blkid won't show anything unless the storage has been formatted with a filesystem first. It doesn't matter what filesystem is used, only that there is one.
If you attach a USB keyboard you should be able to run commands. It's attempting to follow the boot=UUID=UUID-5BE6-0135 param to mount /flash and the SYSTEM file to continue booting. The UUID is presumably wrong and boot params in extlinux.conf need to be corrected.