I can't fix my Napco MA-900 system?

I have a Napco ma-900 system that was working fine. I armed the system went to bed ,and in the morning could not disarm the system. I have three key pads and none of them could disarm the system. I had to turn off the power in order to disarm the system. I have replaced the battery and transformer but still have the problem after resetting the sysytem . All three key pad are dead and have no lights or indicators working. Should I scrape the system or is there a solution I overlooked, Thanks