FIRST unscrew the 4 screws and unclick the black rim from the back shell. It comes off completely, no wires or other screws attached. THEN disconnect the flatcable from the connector on the motherboard. ONLY AFTER THAT heat up the edge and pry off the glass from the rim.
Learned that the hard way. I pried off the glass before disconnecting the flatcable and even though I was very careful it still pulled the flatcable out of the connector which is now broken. Good luck trying to get that fixed… Any suggestions are more than welcome.