ACCENTA 6 PROBLEM...PLEASE HELP!?

I have an ACCENTA 6 alarm system installed and it has worked fine for the last 10 years.

Recently, we had a power cut for the majority of the day & since then, the system hasn't worked properly.

The remote panel (that sets & unsets the system) has the power and day LED lit and so are all the number pads. But, the system buttons (OMIT, SET, PROGRAM, RESET & CHIME) are not lit.

The main box has the Red LED lit, so there is power going to it.

I checked the 12V battery and it was completely drained so I bought a new one and fitted it but this has not rectified the problem.

ANY HELP PLEASE WILL BE VERY MUCH APPRECIATED.