Secondary control panel veritas 8 making a beep?

Hi sorry I have tried to find a solution before posting but can't.
The secondary control panel I have in our bedroom for our veritas 8 has started to make intermittent beeps. It's not often and isn't loud but it always seems to happen during the night!!
I have opened the unit to see if it had a battery back up but it is mains operated only.
There are no tamper lights or issues with the main panel.
Any help would be appreciated
Thanks