Accenta alarm, cannot set system?

Hi, I cut through the cable that was wired to magnetic sensors on exterior doors. This had been disconnected some time ago, as the contacts were not aligned due to wear on the doors, at the control box so I assumed that this part of circuit was dead. As I cut wire, the alarm sounded which I was able to stop by entering code. however, I am unable now to re-set the system and the tamper light remains on and the key pads (two) are inactive and omit no noise when buttons are pressed. Help appreciated please.