How Intel Macs with T2 chips, and Apple silicon Macs can be rescued from the apparently dead by connecting them to another Mac in DFU mode.
DFU
How to erase just the Data volume, the whole Boot Volume Group, all volume’s in the Mac’s visible container, or the entire internal SSD.
One Thunderbolt port is the designated DFU port, to be used when connecting via USB-C in DFU mode, and to be avoided for external bootable disks. But how can you identify it?
You press the Power button, but nothing happens. Has your Mac suddenly died, does it have a problem you can fix easily, or is it just in DFU mode?
Are you intending to upgrade to Tahoe on Monday? Or to Sequoia or Sonoma? Are you ready to cope with what could go wrong? Here are some tips to help you prepare.
How to check there’s no hardware problem, then use Restore in DFU mode to completely wipe internal storage, including firmware, and reset the NVRAM.
Working with external bootable disks: how to create and add them, ownership and LocalPolicy, how that can be changed, and what happens with errors and failure.
Some support USB4, others don’t. Some share the controller, others don’t. Some support DFU mode but then can’t be used to create a bootable external disk on Apple silicon.
Recovery reinstall, using an Installer app, or a bootable installer, or with an Apple silicon Mac in DFU mode? What the choices are, and how best to do it.
When should you put your Mac into DFU mode, hook it up to another Mac running Configurator, and revive or restore it?
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