How to identify & fix my Veritas alarm?

Hi

I have a veritas home alarm that was fitted by the previous owners. during a power outage it started sounding and wouldn't stop so I disconnected the speaker. No I have re-connected the speaker but the system is not working properly, this is what its doing;

Whenever the main point of entry is used, the alarm chirps for several seconds, getting faster then goes silent, and the keypad responds with a 'wrong button' noise regardless of what key is pressed.

I cant see any identification for what model alarm it is other than its a veritas keypad.

so... how on earth do I identify the model, and how can I fix the thing?

Thanks....