Don't be surprised if this takes a while. Also don't worry about being too gentle with the clips on the case - if they break, they will still be held in place by the screws we've just taken out

The first shot shows the area around the hinges - I recommend starting here. Just beside the left side of the battery I found it especially stuck... you'll probably need some heavy use of your spudger, just be cautious when using a screwdriver as it can bend the plastic permanently