Unfortunately, based on the pictures, it would seem that the holes are pretty stripped. The size of all VESA-specific mounting bolts should usually be between M-4 and M-10, and for plasmas, the sizes are M-8's. That bolt is clearly not compliant with the VESA standard.
If the TV still powers on, you may not have "ruined" it (although, it'd be difficult to know why the bolt got hot, and what the effects of that might be long-term), but I wouldn't suggest mounting the TV on the wall at this point with the support of stripped threads. Either an exchange from a sympathetic retailer, or a service call to replace the back panel of the TV would give hope of having the TV mounted on the wall.
I just bought my tv a week ago. Excited to get it onto the TV mounting stand, I went to the hardware store and bought what i thought were the right bolts (TV stand did not come with the bolts). I then tried to screw in the wrong size bolts to secure my Samsung pn42c450b1d plasma tv onto the tv mounting bracket. I took a break because I couldn't get the bolts to go down any further.
I came back three hours later to remove the bolts. I noticed that one of the bolts was hot. I then noticed that inside one of the holes in the TV where i tried to screw in the bolt it seemed to be cracked inside.
Did I just ruin my tv by trying to screw in the wrong size bolts?
What should I do?
Please help... i just got my tv and I hope I didn't ruin it.