If you're an advanced user who is comfortable with UNIX, you can use single-user mode or verbose mode to help isolate issues related to startup.
- Hold down one of these key combinations on your keyboard immediately after pressing the power button to turn on your Mac, or immediately after your Mac begins to restart:
- Command-S: single-user mode
- Command-V: verbose mode
- Continue holding the keys until you see white text on the screen.
- If you're using FileVault, release the keys when you see the login window. Then log in to continue startup in single-user or verbose mode.
- If you're using a firmware password, you must turn off the password before you can start up in single-user or verbose mode.
- You can now enter UNIX commands. To exit this mode and start up normally, type
reboot, then press Return.