Accenta G4 13V supply issues?

Hi there,
I have recently purchased, installed and configured an Accenta mini G4 intruder alarm. All was working fine for the first 2 days. Now I realised that the 13V supply on the main board supplying the PIRs, the external inputs and the siren is gone - the supply to the RKPs is fine. I checked all 4 fuses with a multimeter and they are ok. The panel is functioning ok otherwise - i.e. all functions being set from the keypad are responding fine. The thing is that the PIRs and the siren are not functioning due to the supply issue.
Any help on the above?