The screw doesn't touch the bottom of the battery during the locking-unlocking operation, except if you keep the button pressed on purpose and I can't imagine, why someone would want to do that.
OK so I think maybe I'm having a problem? When I put the bottom together, and just twist the switch on & off without the bottom piece connected to anything, the screw spins. Spins when I lock it. Spins when I unlock it. So imagine the same occurs when it's all put together? Clearly I'm doing something wrong