In certain situations, an Apple silicon Mac may become unresponsive or enter a "boot loop" - a state where it constantly restarts itself and only shows you an exclamation point or an Apple logo. In such a state, you can often reboot the computer into Recovery Mode to attempt a repair or reinstallation of macOS. If you can't, or if the reinstallation doesn't resolve the issue, we need a more powerful tool.
Apple Configurator for Mac allows you to plug in an Apple Silicon Mac to another Apple Silicon Mac to use one to repair the other. This functionality is so helpful that Apple built it into macOS 14 Sonoma - let's review some of the key terms around this process and how it looks in practice.
Apple Configurator for Mac
This is a free application you can download from the Mac App Store. While it has many uses, we'll focus just on resolving issues on other Macs.
DFU Mode (Device Firmware Update)
This is a state you can put an Apple Silicon Mac into that allows another Mac to interact with it as if it were an accessory or peripheral. Once a device is in this state, you can try to revive or restore the operating system via Configurator on another Mac.
Apple summarizes this quite concisely:
A revive updates the firmware and updates recoveryOS to the latest version. A revive is designed to not make any changes to the startup volume, the user’s data volume, or any other volumes. User data may be retained if recoverable.
Reviving a device is ideal if you want to resolve an issue without erasing it.
Once again, from Apple:
A restore updates the firmware, updates recoveryOS to the latest version, and erases and installs the latest version of macOS on your internal storage. When this process is complete, any data on any internal volumes is unrecoverable.
If a revive isn't enough to get a device operational, a restore is the way to go. The Mac will need to be set up as if it were a brand-new device once complete.
If you're performing either a revive or restore, you'll need an IPSW file as the source of the firmware and recoveryOS files. IPSW files are published by Apple for download, and there are different files for most versions of macOS. Please note that you must use an IPSW of the same OS your Mac is currently running or newer - if there's no available IPSW for the OS your device is running, you'll need to use a newer one.
Apple hosts these files on its content distribution network, so finding the links can be difficult. Mr. Macintosh's blog offers this very helpful download page with links to the available files hosted directly from Apple.
Apple has a very detailed guide to this whole process here. I'd recommend moving over to that article to proceed - below we'll highlight some important bits, but you'd be better served following their guide. To summarize, in a few steps:
- Connect the symptomatic Mac to the Mac running Apple Configurator or macOS Sonoma via USB-C
- Restart the symptomatic Mac into DFU mode
- Perform the revive or restore on the symptomatic Mac
- Once the revive or restore is complete, disconnect the symptomatic Mac and restart it
Step 1 - Connect the symptomatic Mac to the Mac running Apple Configurator or macOS Sonoma via USB-C
Be sure to use a supported cable - Apple states that Thunderbolt 3 cables aren't compatible with this process, but USB-C cables that support data and charging will work. Note Apple's very detailed list of which port to use on each Mac - if you use the wrong port, the Mac will not show up.
Step 2 - Restart the symptomatic Mac into DFU mode
Once connected, you can reboot the symptomatic computer and follow Apple's instructions to put the device into DFU mode. There are very different instructions for portable Macs, iMacs, and Mac Studio/mini devices. When successful, you'll see the symptomatic Mac in Configurator:
If you're working in Sonoma, the Mac will appear in the Finder sidebar:
Step 3 - Perform the revive or restore on the symptomatic Mac
You'll now want to begin your revive or restore. In Configurator, you can right-click on the Mac, go to Advanced, and select "Revive Device":
If you've downloaded the appropriate IPSW file in advance, you can drag and drop the IPSW file onto the large "DFU" icon and then select "Revive" or "Restore" based on your needs.
In macOS Sonoma, click the appropriate button to revive or restore and you'll be prompted to select an IPSW file. Remember to only use IPSW files of the same version of macOS or newer.
It's generally worthwhile to attempt the revive before the restore if any user data needs to be retained.
In certain situations, you may have to revive a Mac using a newer operating system than the one it currently has. If this comes up, perform the revive as usual, and when you restart the symptomatic Mac, you will be brought to a screen where you can either startup to your boot volume (usually Macintosh HD) or select "Options" - please select the "Options" item to reboot to the recoveryOS and reinstall the new operating system. This will upgrade your OS to the same version your IPSW file had - a very important step for resolving some issues.