how do I fix my accenta G3 alarm?

My accenta G3 alarm accidently got set off some months ago. Despite trying to reset it, the blue outside light has continued to flash, but the alarm still worked.
Now it has stopped working (blue light still flashing). I entered my code when I entered the house and all was fine. When I tried to set it to exit the house, the red light for zone 4 was on and no noise was made when I pressed the buttons to set the alarm.
Help very much appreciated.
Thanks.