Sorry for using that terminology.
Basically you force the panel to recognise the factory default user/engineering codes if all other preprogrammed codes are lost or forgotten.
Theres a procedure that may or in some cases allow you to try this, but you will need the engineering manual,
IIRC the 300 series can grant temporary access using the factory default codes,without the need to fully reprog the system back up again like most panels that have been crashed (forced factory reset).
Find the engineering manual and just think "link" as you are reading through it.Sorry can't tell you what to do on here for security reasons,also I'm sure one of the engineers who use this site will no this panel more than me,and correct me if I'm wrong.
It's been a while since I've had any contact with the 300 series.
Other option is to get an engineer in but if you don't care for the system then just shut the system down,mains/battery then let the outside sounder ding a ling until it's battery dies,or ladders out and pull the battery from the sounder.
Simples... Hope this helps.
Good luck :)
e manno, October 2013
