If your Mac doesn’t start completely

Fortunately, a Mac that does not start completely is an exceptional situation. And that’s exactly why the necessary knowledge to solve the problem is not always immediately recalled from memory. To support the gray matter and those who have never been in this situation, here are a few possible solutions.

A Mac as an external hard drive

Do you (temporarily) have a second Mac (Mac mini, MacBook Pro, iMac,…) at your disposal? In this case, you could check whether your “(still) not completely starting Mac” is at least able to boot in “disk mode”. Then there might be a very simple solution…

You can connect an Intel-based Mac to another Mac so that the Intel-based Mac appears as an external hard disk — known as target disk mode. You can then transfer files between the Mac computers.

If the above - super simple option - has been applicable, then you don’t necessarily need to read any further from here. You can now simply copy your valuable data from the “external hard drive” (which in reality is a complete computer).

Recovery, Installation

If that didn’t work or you want to be able to start your Mac again after rescuing your data, then let’s continue with the explanations from the official Apple Support pages:

• If your Mac doesn’t start up all the way [2]
• If your Mac starts up to a question mark [3]
• Reset NVRAM on your Mac [4]
• How to start up from macOS Recovery [5]

6. When your Mac has successfully started from Recovery, it shows a window with utilities such as these:

• Restore from Time Machine
• Reinstall macOS
• Disk Utility, which you can use to repair or erase your startup disk.
• Other utilities, such as Terminal, are available from the menu bar at the top of the screen.

Once at this point, Disk Utility can be used to prepare a part of the hard drive for a second macOS installation. After that the actual installation of macOS can take place. The resulting operating system instance will be independent of the existing installation. At the end of the installation, the computer starts automatically and displays the setup (select time zone, connect Wi-Fi, iCloud login or registration, ….) - as if the computer had just started for the first time after unpacking it. Now you can login with your user (that you’ve created in the setup process, e.g. “Thomas Anderson”) and browse the hard disk (Volume „Macintosh HD“) content for your data. If „FileVault“ (a „Security/Privacy Mechanism“) is enabled, then the corresponding password is required.

The prerequisite for the processes mentioned is intact hardware and that the macOS recovery can be started.

Additional information about Disk Utility:

• How to repair a Mac storage device with Disk Utility [6]
• Disk Utility User Guide
  • Repair a storage device in Disk Utility on Mac [7]