The battery screws on these machines are not a normal 6-pointed Torx screw. Unfortunately the 5-pointed type screw that this machine uses is patented and screwdriver manufacturers will not sell them to the general public. Apple's clearly chosen this screw because they don't want you removing the battery. We'd love to offer the screwdrivers for sale, but haven't figured out any way that we can legally do so. The good news is that in our testing we were able to remove these screws using a 1.5 or 1.6 mm flathead screwdriver, so that's probably your best bet.