The two screws with plastic heads fit at the top of the door between the rear panel and the middle panel. They screw into the front panel through the middle panel and the screw head pokes into the rear panel so you can tiurn it from there.
I worked it out eventually!
My problem was that there were two weeks to forget between taking the door to bits and fitting it up again because I did not have the sense to buy a new seal ring at the same time as the replacement glass panel.
Roger
December 2017