It sounds as if the ATV2 is waiting for a tethered boot to be performed!
The 5.3 jailbreak is a ‘tethered’ one which means that any time after power has been removed (or after a hard reset) you will need to connect the ATV2 to your PC/Mac via USB to use SeasonPass to do the tethered boot steps. This means that the process must be done with your ATV2 where it is going to be used so that power can be left connected.