How to fix my Micromark MM9495B 7 Zone wireless burglar alarm?

I turned off the mains and when I put it back on the alarm froze. The standby battery was very old (hooray for Microlyte) so I've bought a new one. However, it still isn't allowing me to re-set. The beeper doesn't happen when touchpad is pressed. There is a red light on the bottom of the keypad and a green light flashing intermittently inside the box behind the circuit board.

Fifi
November 2011