So i bought a macbook off of a guy from craigslist.. I was playing on it yesterday and all of a sudden it resets and there's a pin code or something. I call him and he tells me to take it to apple. He told me he bought it for his girlfriend and sold it because he had bills to pay and she was selfish and i don't know what to do. What should i do take it to apple? I have the Snow leopard Disc but cant boot it since its a 2011 macbook and i cant get around the firmware password. Is there anyway i can check the serial # to see if its stolen?