Noises are doing my head in....my question is about the small grille on top of the dash that clears the inside of the screen. I've tried taking it out and can't as it seems like it's screwed in but cannot see any. There also looks to be a small sensor of some kind under the plastic cap that looks like a screw would be under that - what it is and what does it do ? I've just snapped the cap so the sensor is now 'open'.

Ta !