Alarm Problem (IntelliSense Securit 800L)

I have an IntelliSense Securit 800L house alarm installed and following a recent power cut, the mains light on the keypad is not alight. When I press the keys, the pad beeps and the backlight comes on, but alarm does not set.
Could this be the fuse and or backup battery. The battery is quite old.
Thanks
PS All PRI’s are working.

If the backlight comes on I can't see it being a fuse. Does the alarm accept your code? If not it may have reverted to the factory code. (iirc it's 1234.) All old batteries should be changed as a matter of course. Does the keypad bleep when you press the buttons?

Thanks for info Joe-90.
The alarm does not accept my code and I have tried entering 1234 without success.
I will replace the battery anyway.
Yes the keypad does beep when \I press the buttons.
Any other suggestions would be appreciated.

Hi Tipson. I have exactly the same problem following a power cut. Panel lights up with green backlight, and beeps when buttons are pressed, but no Mains or DAY or TPR LED. Doesn't accept my code or default code. The internal battery seemed to keep the alarm panel powered for only 10 mins, then all the LEDs flickered and the alarm made a fairly pathetic wail, then gave up completely. The system didn't recover after mains power was restored, in the same way you described.

The internal battery (which i replaced in 2017) only had 8.5v on it so either it's not charging because it's too old, or the PCB is no longer charging the backup battery. I'll replace this anyway. In 2017, i'd also noticed that the transistor on the heatsink had blown up, I assume it had been working too hard to charge a previously faulty battery so I soldered a new one, and have been trouble free for 9 years!

But what did you do to fix your system?