fault lockout on an accenta g3 alarm?

HI, MY HUSBAND WENT TO SET OUR ALARM AS USAL THIS MORNING, it then started going off for no reason, he tried pressing numerous buttons to shut it up which eventually worked, including turning fuse for alarm system in main fuse box off then back on again.

At the moment all that is lit is the green day light and the red power light and nothing else. when you press keys on the box on the wall nothing happens.. is this lockout? how do we fix it. When you turn the fuse in main fuse box off and then on again the box does beep and one red light under no6 stays on but if you press reset it disappears and then nothing will work as before. Any help greatfully received as really dont want to have to contact the installer who charges £170 call out charge!!! System is 7 years old and has never had any problems before.