I have had this old Macbook Pro (2011 Model I think) that my brother gave me a while ago because he didn't know what was wrong with it. When I try to boot it up it is just stuck in an infinite loading screen. I think it is a hard drive failure or something but I have no knowledge of how Macbooks work so my opinion means nothing lol. Also if I want to power it on it HAS to be plugged into the charger so I guess there is something wrong with the battery too? Anyways I found the OS X install disc today so I was able to boot up from that and start the install for OS X but 2-3 minutes in the install fails without really giving a specific reason. So I go to the Disc Utility and try erasing the Macintosh HD but it comes up with a failure to erase because it could not unmount the disc. I have no idea what to do from here. If someone could please help or give any guidance that would be awesome