I had similar issue. We live on a estate which was built approx five years ago, so all the alarms were installed around that time. Recently we had power cut, and the alarms went off, due to the backup battery in the controll panel dead. This probably needs to be repalced every four years. I ordered the battery from www.tlc-direct.co.uk. Replaced the bettery, and then although the keypad lights came backon, but pressign any buttons would not do anything, similar to the problem experienced by the original questioner.
This is what I did:
1. Remove all power (I switched off at the mains) including the backup battery.
2. On the control panel (not keypad) remove wire/s from 17 (mine was red) and 27 (if any).
3. Using a spare electric wire approx 12" long, inserted and connected up 17 to 27 (looped)
4. Connect battery and switch main power. The alarm will go off.
5. On the keypad enter your user code. This stopped the alarm and all was normal.
6. Take extra care as the system is now live (not recommended but this is what I did) - remove wire from 17 and then 27. Do not touch live wires.
7. Re-insert the red wire in 17, and 27 (if any).
8. Put the battery in close the control panel cover.
All should be back to normal.
Test alarms by switching off the mains and/or by setting various zones, etc.
I am not much of a DIY person, but managed to follow the instructions in various manuals and Google'ing the internet.
QED.
mmukadam@hotmail.com
mmukadam@hotmail.com, December 2005