Cat 2= imobilizer
CAT 1 = alarm-imobilizer

So the cat 2-1 that you have is....

A cat 2 imobilizer, that in order to gain cat 1 status has had an add on fitted to make it an alarm rather than just an immobilizer.

My guess as the imobilizer is still working, the ararm unit may have blown the fuses, try that first, then try the batterys in the handset, then you would need to enter the self code setting and try re entering the handset as it must have lost the code.