Looks like image authentication issue.
Most likey, your device has the old authentication key and you are trying to upload bootloader signed with the new key.
If the device boots up with the old key, you can either update the key /or delete it and then apply the new bootloader.
If it is not even booting up and stuck at the 'OS Loader File Name ' prompt, you need to contact JTAC and obtain old bootloader to recover the box.