I am hoping someone on this site may be able to help me. I am not familiar with tools, screws, bolts, nuts, or wrenches. I bought a grill from Sears and they built it for me. I brought it home and, long story short, they put the ground wire under the wrong screw. The correct screw has some sort of nut or bushing or something on the back that is stopping my stronger family members from unscrewing it to put the ground wire where it belongs. Sears reps are demanding more money and even screamed over the phone at me, so I would like to do it myself.

Story version: What is this and how do I remove it?? I have pictures from different angles if necessary.

Back of the correct ground wire screw

Slightly stripped ground screw that won’t budge

Attached Images