HELP? On how to repair my house alarm, a Melcom ST6100 ?

I have power supply to my alarm contol panel but my alarm siren will no longer activate, when my system is in alarm mode and there is a forced entry, also my front door connectors no longer beep, when i enter the front door.
The alarm system was working perfectly until we had a lightening storm which caused the alarm siren to go in to operation. So would a lightening strike, on the alarm box outside or on the house cause this to happen and if so, how can i repair the problem? Thank you for any help.

Bazza
January 2011