house alarm system?

A few months ago we bought a house with your system. Unfortunately the previous Occupants failed to leave any info on the security code. A few days ago the alarm went off when an electrician turned the main fuse board off. After reconnecting the alarm pad which is placed by the front door failed to show the amber and green lights which were on it before the alarm went off. We have no knowledge of previous code. Is it possible to send an engineer.