Starting from the bottom corner, use the thin blunt side of a Spudger to separate the back from the metal bezel. THIS CAN CAUSE COSMETIC & INTERNAL DAMAGE if you are not careful.

Use a thumb nail, plastic spudger, or pry tool to raise one side releasing the plastic clips. Then raise the other side and the top should pull off with ease.

During reassembly the back may fight a little to go back on. Start from the side and go around do not be afraid to pinch it with a little muscle.