how to fix accenta 6 alarm?

My husband stupidly took the key pad off the wall for DIY, not realising it would set off the alarm . In a mad panic and a major strop, he managed to stop the alarm, but also pulled out wires left right and centre. He has rewired it, we have power in the main box, but not in the key pad (no lights on), but it is making a feint alarm type noise. Any ideas?