It's likely the 12v gelcell backup battery was on it's last legs when you chopped the cable. This makes the alarm rely on the battery alone. If the battery was failing and gone short circuit or low resistance, it will have fried part of the charging circuit - in particular a large carbon film resistor of around (I think) 10 ohms rated at 1 watt. You'll probably see that it's cooked - this will have occured when you power the panel up again.
You need a new battery and a new resistor, but I would get someone competent to check out the rest of the power supply section of the panel first.
You may well have to do a complete system reset when you kick off again.
The other possibility is that in chopping the power cable you've 'spiked' the on board eeprom and corrupted it's contents. A reset may sort this problem. Do this first as it's easier and cheaper!
John J, July 2009
