Apply a suction handle to the bottom edge of the rear glass, while avoiding the very edge of the glass.

Pull up on the suction cup with firm, constant pressure to create a slight gap between the rear glass and the frame.

Insert an opening pick into the gap.

The adhesive holding the rear glass in place is very strong; creating this initial gap takes a significant amount of force. If you're having a hard time opening a gap, apply more heat, and gently rock the rear glass up and down to weaken the adhesive until you create enough of a gap to insert your opening pick.