Some models have a small GSM flex cable (Shown in the 1st picture, circled in red). There is a piece of tape covering it and will need to be removed. Then underneath the tape, there is a small tab, which is closest to the LCD screen. Lift gently on this tab with a smudger tool. In a later step, the flex cable will be removed from the board.
Remove the screws from the metal plate on the power button, and gently detach the connector where indicated. During the removal, the metal cover and the rear facing camera may come out together.