If you ever start up your Mac only to eventually find yourself staring at a blue screen and a cursor, you've just encountered the Mac's version of the Windows blue screen of death.
No matter what you do, short of turning your Mac off, the blue screen will just sit there, as if waiting for some magical command that will allow your Mac to continue the startup process.
Unfortunately, there's no magical command that will make everything okay. But fixing the problem may be easier than you think. The cause is usually a problem with the startup drive. This guide will take you through the troubleshooting process and help you get your Mac running again.