This alarm is in a house I recently moved into, I don't know how old it is or when it was last serviced. The power supply was accidently switched off by a workman. A few hours later the alarm began to emit a noise which I now think was a signal that the battery was getting low (Never had an alarm before so had no idea) eventually it stopped. Having read the operating manual several times and checking various wiring routes I found the switch that had been turned off. When I turned it back on the alarm started making the same noise again. Assuming that the battery is now dead, will I have to get a new battery fitted before it can be turned on again. If so, any ideas on how much it will cost to have it fitted?