Ok heres the deal.... I just purchased a MBA of craigslist from some random guy. He was selling it because he needed rent money.. so he said. Anyway it was running fine until it randomly said it needed to be restarted so i did it. After the restart i got a blinking folder with a question mark. After some searching i figured out how to boot from an external hard drive. I went to the apple website to check the status of the warranty and to my surprise it was still covered under the limited warranty. Now after a careful inspection of the underside of the mac i noticed several scratches around the screws, one screw is missing, there is a bend in the case as if someone attempted to open the computer before and the screws on each side of the mac in the do not sit flush like all the others . Would any of what i found void the remaining warranty on my mac? I attached some pix of my findings.