Apple warns in a support document that current Mac computers, in which the security chip T2 is installed, can only be "revived" by a complicated process if there are problems with firmware updates.
The Hints can be found in a manual for the current version of the configuration tool Apple Configurator 2to which the technology blog Eclectic Light Company on the weekend encountered is. It can therefore happen under "very rare circumstances" that the T2 security chip in the Mac no longer responds and that the firmware must be replaced. This can happen, for example, if there is a power failure on a desktop computer during a macOS upgrade – however, it is also known that Macs sometimes do not get the latest firmware installed for other reasons that only Apple knows.
Just one port – and one key combination
A firmware restore is necessary if the Mac can no longer be started up from its start volume or the recoveryOS partition or if an internet-based recovery process fails. In addition, a firmware revive is also possible, in which it may not be necessary to completely reload the existing macOS.
A second Mac running Apple Configurator 2 is required for both firmware restore and firmware revive – as well as a suitable USB-C cable. There are separate routines for MacBooks, iMac Pro, Mac mini and Mac Pro, which Apple describes in its support document. So you have to use the correct USB-C port and, depending on the model, press a certain key combination at startup to put the machine in the necessary DFU mode (Device Firmware Upgrade).
Revive or restore
You can then start the Revive or Restore process with Apple Configurator 2. With a firmware restore, the internal flash medium (SSD) of the Mac is also forcibly deleted because the encryption key required for this is also removed from the T2 chip. A restore accordingly requires a complete new installation.
The T2 security chip is found in all current Macs – iMac Pro, Mac mini from 2018, Mac Pro from 2019, MacBook Pro (13 inches from 2018 with four Thunderbolt 3 ports, 15 inches from 2018) and MacBook Air Retina (from 2018 ).
. (tagsToTranslate) Apple Configurator (t) Apple Configurator 2 (t) Apple T2 (t) EFI (t) Firmware (t) Firmware Restore (t) Firmware Revive (t) Mac (t) Thunderbolt (t) USB (t) macOS