Hi I have an ‘optima XL 4’ in my house it’s been there since we moved in. As far as I was aware it didn’t work for whatever reason. We weren’t bothered by it so never touched it. Previous owners said it was broken and therefore we never got a code off them. However today my kettle tripped my electrics and when the electrics were turned back on, this ‘broken’ alarm decided to come back to life, it’s beeping constant. However it’s really quiet. Can anyone help?