MacBook dead? Student life destroyed.

earlier when I left class I closed my MacBook, and put it in a padded bag. When I got home, the MacBook was

really hot, and the fans were on. It's since cooled down, but now it won't turn on at all! The power cord lights up when I plug it in, but that's all the response I can get out of it. I don't know what could've caused it to heat up so much in the bag (it was only in there for fifteen minutes, and it was shut down besides). Have I permanantly damaged my MacBook?