MA
If it restarts by itself then it will probably be based on timecode, in other words if the incoming timecode is 22:15:00:00 when the power is restored the server will attempt to play from 21:15:00:00. There may be nothing at that timecode on the server depending on how long the power failure has lasted. No timecode present may result in the server simply doing nothing at all until there is manual intervention, or it may output black during the period of TC loss. Of course there is also the possibility of it doing something rather random because of the unmanaged power failure.