I was given a Thunderbolt 15" Macbook Pro with missing shift keys as a broken project to do with as I wish. Now, the machine powers on, but it won't boot OSX. It goes through these steps: 1. White screen for about 30 seconds 2. Black Windows error recovery screen offering to Launch Startup Repair or Start Windows Normally Launching Repairs leads to "windows loading files" Then a Safe Mode looking repair utility pops up for Startup Repair "Your computer was unable to start" It tries doing this for a few minutes, then says it can't auto fix. Computer shuts off. Start again and at the black screen choose normal startus, computer never goes past the "starting windows" screen. Now, I'd like to put this thing back to OSX, but I don't know where to start. Any advice from you guys and gals?