I have a friend that moved in to her house a couple years ago now and she has told me a few times that her intruder alarm has gone off even though she never sets it.

I have told her it most likely needs a new battery and offered to change it for her, I'm quite competent with electronics but upon researching the model (Veritas R8) discovered that you need to remove the access panel and after doing so will trigger the alarm (understandable) and need to enter the engineer code.

Problem is the previous owners never gave her an engineer code, just her code which is 1234, coincidentally the default engineer code for this model.

I'm thinking maybe entering her own code will disable the alarm? If not what are my options, kill the house power? But I'm guessing it'll probably restart when we turn the power back on. Or is the only option just doing it and pissing off the neighbours for half an hour until the timer kills it?

Just looking for a bit of advice if anybody can help? Needs to be changed one way or another.