The hidden feature that enables you to remove the back is hidden under 2 little square 'bumps' at the bottom of the rear cover, if you insert a screwdriver through the opening on the RHS, the back pops loose. Wedge the back open with a guitar pick or spudger and do the same thing on the other side. Once it's loose, you can use a spudger to release all the clips along the left, right, and lower edges (5 each side and 8 along the bottom).
This doesn't appear to be documented anywhere that's readily accessible!