Knauss Sky Ti - change a light bulb

Seems like the easiest thing to do but for the life of us we can not work out how to get past the cover. I am guessing they are standard on most motorhomes but we did not have them on our last one and do not want to risk breaking the cover trying to get into it. We have even searched through the manual and there is nothing in that either ( and it tells you how to open and close the window blinds !!). If anyone can give us a clue it would be greatly received before we ring the dealer. It is a flush round spot light cover with LED lights underneath. Bizarrely 2 have gone out on this trip at the same time.