Mine has just started doing the exact same only yesterday...You can still use the alarm by following the power fault instructions.
1. input 4 digit code or just press full (depending on ow you usually set your alarm). You will hear 10 quick tones.
2. Press omit button
3. Press 0 button
4. Press Prog button & the usual armed alarm noise will sound. Leave premises & when you return do whatever you normally do. The power/unset button will continue to flash but this works.
I just go through this procedure whenever I set the alarm.
Hope it helps
Kazzybee, July 2007