veritas alarm cannot be reset or accepts code?

I had to disconnect power on house electrical board in order to fit new sockets switches and dimmer switches for obvious reasons.

In doing so the Veritas alarm was triggered, and would not accept alarm code to silence. The audible alarm was inside and not outside. This went on for some time and the zone lights all illuminated on the control panel. Still would not accept alarm code to silence. It then went silent, and then sounded again.

Eventually, the alarm stopped, but now I have the red zone 1 light showing, green light on front of panel illuminated, but now when I depress any button on the control panel there is no sound at all to indicate if the alarm is working or not.

Any ideas please?