Screws on the motherboard making noise
Screws on the motherboard making noise
Remove the last two screws just before it clicks again, pulling the motherboard gently while keeping the standoffs in place. Use pliers as usual to take out and replace them. Extra tip: if the screws are tight, apply a bit of WD40 to the heads and try turning them gently—some may be cross-threaded.
From what I understand, the screws aren't cross-threaded but are stripped. If it stops turning after reaching a certain point, it likely means the threads have been damaged. The best approach is to attempt to remove it while applying some pressure, pulling gently as you unscrew. Be careful and good luck!
If you're not worried about harming the screw hole's threads on the PC case, you can always attempt a forceful push from the back side. Use a small object that fits into the screw hole and a mallet. Ensure you hold the motherboard securely so it doesn't fall and get damaged when the standoff comes out.