GE fridge warm freezer cold

The fresh food compartment is at 50, freezer at -6. Suspecting a bad defrost heater as the resistance at the board was in the megohm range. What the best process for getting the back panel out of the freezer? Looks like the ice maker is held with screws in the side wall. The back panel is held with just one screw?? Don’t want to break it taking it apart…

Thx,

Chuck