Do not completely separate the back panel from the camera. There is a ribbon on bottom left back corner underneath the buttons. The ribbon will hold the back panel to the camera. Do not jam the tool in this part or the ribbon will rip.
Use the metal spudger to pick the bottom of the plastic piece while simultaneously using your index finger to push down on the larger metal slab. This will cause the metal plate with the large ribbon to slide down and out of the plastic back panel.