How do I remove this room sensor?

[potato80]

Hi all

This room sensor is connected to the wall above the door frame; but I can't figure out how you remove it. I'm painting and light plastering the room, and need to get behind the sensor to make a good job of it.

There is a little screw (pictured), but I have no idea how you get to it!

Any help much appreciated

 

[secureiam]

whilst in engineering, undo screw at the bottom, lift front cover off, then see how its screwed in, may need to remove pcb screw to move pcb to get to screws.

 

[secureiam]

well I see you have undone the screw, slotted screwdriver or nail to help remove front cover.

 

[potato80]

Thanks, I'll try removing the cover and see what I can find. I can't reach the head of the screw directly underneath the unit, because it is against the frame of the door..