9448+ "style" Scantronic alarm system?

A bit of advice needed really?

We are currently doing some decorating at home. I started trimming the edges away of our stairs carpet (ready to prep and paint the skirting boards) and appear to have disturbed a wire that was running along the edge of one of the steps. This has triggered the burgular alarm, and now it won`t stop. There are no signs of any cut or mark to the insulating cover or the wires inside.

As soon as it started ringing I went to the key pad (that we use to activate/deactivate the alarm on entry and exit) by the front door, this wasn`t illuminated as it always is and inputting the code didn`t stop it. There seems to be no power getting to the keypad or any of the motion sensors on the walls. However, the alarm box inside the house (not the key pad) seems to have power but opening that and unplugging the back up battery stopped the alarm inside, but now the box on the outside of the house is still ringing. I`m guessing that there has to be a back up battery in the outside box aswell?,