Bongo Fury

At 2am the alarm started going off.
The phob won’t switch it off. Unlocking the van had no impact. So I disconnected the primary and leisure battery
It’s still going but much quieter. Where would I find the alarm and it’s backup battery?

Any ideas why the alarm wouldn’t switch off?

Sadly, this is impossible to answer without at least knowing the type of alarm.

Plus, the fitter will have put it where he felt best.

The back up battery is normally located internally in the siren itself, follow where the noise is coming from but in most alarms the siren is sealed.