So I was updating to OS X Yosemite the other day and it froze on install. Now when I try to startup the MacBook it flashes some code in the top left then goes to a black screen with an apple watermark and says your computer has encountered a problem and will attempt to reboot. Press any key or wait to reboot. Has this happened to anyone? Any tips to fix? I can't get it into recovery mode either by holding shift or x.