Hi, first point to note the battery (if checked and maintained) should last more than a few hours without mains power to the control panel
If you have fully drained the battery then when you have switched the power back on to the unit it may of blown the quick blow fuse (next to the transformer) I think this is 125ma (but it does say on the label) l
if you are electrically competent & know what you are doing you could check this First
if not call the experts