It took ages to work it out... open up the face place (which houses the light bulb), and there's a big shiny knob in the back corner - press it. And it pops the top right off! Meanwhile I'd been pressing a latch I thought was a lever, and discovered the face plate wouldn't stay shut again - oops! Pleased to get the top off to re-position that little catch... I know this is an OLD post, but I came across it in my search, so hope someone else finds this helpful!
Michelle
December 2014