Gardtech 800 Alarm?

Our alarm previously worked perfectly.

A chip ID no 4 in one of our Fire Detectors was damaged by the service engineer when replacing it with a new detector. We have sourced & fitted a replacement chip but now the system isn't working properly and he says we need to update to a new system! Will this have damaged & caused all the ID chips to fail? What do we need to check in order to locate the fault.