Purchased a macbook pro off craigslist(never do that again) turned it on and it looked good but when i got it home and connected to my internet it locked up on me and asked for a 4 digit pin that i didnt have so upon searching google i found out it was an efi/icloud lock I thought i had a $600 paperweight until another google search uncovered a solution. I sent my machine to a computer repair spot in NJ which I found at ******cityrepairdotcom and when i got it back it was like new. Thank goodness for them so if u run into this problem I suggest you give them a call 2012221055