According to the Apple user guide for replacing the hard drive, they don't mention taking out the battery - probably why the battery screws are of the less common tri-wing screw. Even though you're trying to prevent a potential shorting of the logic board while taking out the hard drive, you are also risking a short by trying to take out the battery (which seems the same difficulty as taking out the hard drive).
Since I can't find the tri-wing screwdriver, and the Apple manual doesn't say to take out the battery, I will just be careful taking out the hard drive.