Keypad is beeping, don't have the code?

My house has got an alarm system fitted which was there when i moved in. I've never had any code for it or manual. The only thing it has ever done before is the keypad beeping when the power has gone off. Today its beeping again but power is on. I tried isolating it from the mains but this set off the alarm on the wall outside, so i turned it back on. From looking on the net i think the keypad is a scantronic 9930. Is there anything i can do to stop the beeping? I'd really like it isolated from the mains and all the batteries out so notting can ever go off. Can anyone help?