The mother screw right underneath the IO panel is stuck to the standoff underneath it. When I try to unscrew the screw, it spins together with the standoff underneath it. After one or two rotations, the screw/standoff makes a loud pop and goes back to where it was originally. I checked the backside of the case and saw that the standoff hadn't quite gone through the entire motherboard panel.
The case is a Fractal Design Arc Midi.