At this point, you should be able to grip the back cover and release its remaining clips. If not, slide a pick under the perimeter of the back cover until you can grip an edge.

Grip the left edge of the back cover and lift it away from the eReader to release the remaining clips.

Remove the back cover.

During reassembly, align the back cover over the eReader and press along the perimeter until all its clips snap back into place.