Possible to lose jailbreak on a 5.2? (untethered)

I had a very odd thing happen to me. I have a jailbroken 5.2 ATV that I did a reboot on (pressed DOWN and MENU key) because it froze when trying to install new skin. When the ATV rebooted it only came up to the apple logo and then just black screen with the light flashing. I unplugged and plugged back in but same result. When I checked it in tinyumbrella it listed it as invalid. I tried kicking it out of recovery mode but that made no difference. Please note 5.2 is a untethered jailbreak and I’ve rebooted this unit a few times this way with no problems.

Is there something I did to lose the jailbreak? Can it even be possible to lose a jailbreak this way? In the end I re-jailbroke it and it’s working fine now, but I’d like to avoid this in the future.