http://www.guardianalarms.net/home_security_manuals/ADE/Optima_G3_v2_Installation_Manual.pdf
http://www.securitymattersuk.com/support/Intruder%20Alarms/ADE%20Accenta%20G3%20User%20Guide.pdf
The above may help. From my G4 system I think you have to short out a couple of jumpers on the main alarm board during complete power up.
Mike
February 2009