hell yeah dude.
it literally just looks like just a piece of metal.
It's a special piece of metal, with the bottom machined precisely so that the metal contacts as high a surface area as possible. One which you just covered in dirt and dust and carpet stuff. Don't do that in the future; it makes your heat sink not work as well.
The 'USB Device over-current' error message means that the motherboard is detecting too much current going to a USB device. Unplug everything in the USB ports on the motherboard/case connectors and then check your motherboard to see if there's any loose screws or anything that's shorting it out.
It was a bad idea for me to try and do this myself, but hopefully things work themselves out.
It's a good idea to replace your own graphics card. It's a bad idea to go at it all ham-fisted without reading any guides. If you read online before busting open your case, you would have known not to work on carpeting with static-sensitive electronics, not to remove the heatsink from your graphics card, and not to do whatever you did that bricked the USB connectors on your motherboard.
At this point you should just bring it to a shop before you break more stuff.
