If you don't need the case and all else fails, a few carefully placed smacks from a hammer can prove very useful.
That said, It's held together by two screws. They're under the label near the back of the case. Press on the corners of the labels with your thumb to find em, poke a phillips screwdriver through, and pull em out.
After that, the case should open up for you. If it doesn't, make sure the antenna isn't in line with the side of the case, put the side opposite it on the edge of a table, give it a firm smack on the edge with a small hammer. It'll pop right open for ya.