Respuesta a "My MacBook Pro has a black screen at startup."Same issue started happening when i updated to OS X Yosemite on my MacBook pro late 2011 15". The way I use it is with an external monitor, so I'm thinking its a software issue, the reason being is because if I have my Mac in clamshell mode while connected to my mac then unplug from monitor then open lid of Mac and then shut it off. Now when powering it back on my Mac still thinks it's connected to the external monitor and I get a black screen. So to fix Restart MacBook pro if you have your volume up you will hear the usual chime, now your at your black screen from here you must type in your login password blindly hit return when done, type in your password one more time just in case you didn't type it on correctly. If you typed password correctly your Mac will login and your screen comes back to life. And now when you shutdown your Mac then restarting Mac again you will not get that black screen again.