how can I stop beeping noise after power cut?

We had a power cut last night and during the cut and ever since the key pad for the alarm has been beeping every 30 seconds or so. The same beep is coming from the unit in the loft.

The key pad is blank, except I can just make out an ALERT message across the top.

We do not use the alarm but do have the code.

Can anyone advise how to stop the beeping?

thanks