So my sister bought a macbook off craiglist, however the security lock plate thing was broken. she did not notice it until 3 days later (the laptop was in otherwise great shape and didnt bother checking the side). There is a warranty left on it and when check on Apple support site it says warranty is still supported. I call the guy that she bought the laptop from and he assured us it was not stolen and stated if it was stolen it would be on Apple's Blacklist. (No idea what that meant). He also will not offer a refund because its been a week. I do not want to post the serial number here but is there anyways to find out if its stolen? And if it is what can we do about it?