Accenta 6 alarm system?

No pcb available for this alarm panel, well obsolete! However If all worked prior to your work then there’s no reason why it shouldn’t work now. How did you ‘check’ the fuse? Most likely problem caused by power supply/fuse or a connection to the panel rather than the panel itself! What 12v supply are using to check the pirs? External sounder uses a separate fused 12v supply for power.

Alan
March 2023