ok, here you go BE CAREFUL MAINS ELECTRICITY
1. Remove battery (if its connected)
2. TURN OFF MAINS ELECTRIC to the panel, there could be a unswitched spur near the panel if there is take the fuse out, if not inside the main panel next to where the mains wires go in is a black fuse holder. gently wiggle it and pull it out.
at this point the bell may well be going off outside, if its not your laughing it will never go off again, if it is the battery in the bell is powering it. you have 2 choices get up to the bell and disconnect the battery or wait maybe a couple of hours till it stops
warren W J Electrical Jones, November 2009