I am a (retired early) electrician,put loads of brand new alarm systems in over the years. Got a problem with an existing system in a friends house. Said he'd been having trouble for a while and now not working at all.As he has no manuals or engineer code i have replaced the panel with a brand new Accenta G4 panel (c/w LED remote keypad). On firing it up i have found that the external strobe/sounder box is kaput, this i will sort later as my mobility is a bit iffy at the moment for extension ladders. Disconnected bell box for now (and refitted the factory tamper link) which has now cleared my tamper LED on keypad and everything is good to go with power LED and unset LED lit on keypad.For now we are just going to be using the existing (very loud as it goes) internal speaker. Running through the engineer programme menus is fine and everything i ask it to do it does -built in PA works to set off speaker,can set alarm as if leaving/entering etc.However the walk test is a problem. On normal unset mode or set mode the pirs light up upon detection when you walk past them, on set mode they don't set off the alarm even though they have lit up as detected. On actual engineer walk test mode they should programme to the system (flagged up on keypad) as you walk past each one. They do light up as you walk past them but nothing shows up on the pad. (ps- speaker-which works, bell box- which we know doesn't work, and pirs- which seem to half work are existing from the original system but i thought a pir was standard and universal ). Let me know your thoughts you lovely people!!