Roomster 2 beeping from dash

[yaweebeauty2]

Drove for an hour yesterday and today to my parents. On both occasions the car has been randomly beeping constantly, through the front vent, when parked up. Seems to be better when engine is running but still apparent for a while, & beeps in random sequences and speeds. I've attached a sound of the beeping. Recently changed the battery to lion 027 from Eurocarparts as it is the appropriate fit according to the website, it appears to be securely in place too. I also recently switched from the stock roomster dance head unit to an aftermarket kenwood dmx125dab. I unplugged it to see if this was the issue but the beeping continued anyway. There is no parking sensors on this model either. Any suggestions on my next steps? Thanks 

I should add it's a 58 plate 1.4 diesel