My car had a little knock from the rear which dented the boot lid. The alarm on the car now irregularly sounds, usually at early hours of the morning!!

I assume there is some sort of sensor in the boot which is part of the whole alarm system. Is there anyway I can disable that? I will eventually have to replace it when having the repair done so would also be useful to know what part needs replacing. What does it look like? Part number? Name?
Any help on this would be greatly appreciated!