Another macOS update, and for most another firmware update, this time including Studio Displays. These should go well, but what if they don’t? How do you put your Mac’s firmware back in order or get that expensive display working? Should you force a shutdown and try again? Before panic takes charge, take a deep breath and read on.
These have fixed ROM and upgradable firmware with EFI software loaded from any bootable storage. Although that means they can’t support any form of secure boot, it also makes them more versatile to recover when there are firmware problems. They’re designed to have ‘self-healing’ firmware: if something does go wrong in a firmware update, the Mac is supposed to be able to restore sufficient to be functional again. As they can be booted from an external bootable disk anyway, they should be straightforward to get back into action.
The snag is that their firmware can’t be downgraded, only upgraded. If you update your Mac with a version of macOS including a firmware update that proves a disaster, there’s no option to step back. Some Macs, particularly those whose internal storage has been replaced, may not update their firmware correctly; this article explains that problem.
As an Intel Mac with a T2 chip has two processors of completely different architectures, it has two sets of upgradable firmware, EFI for the Intel processor, and iBridge (bridgeOS) for the T2. In the early days of T2 chips firmware update failures weren’t as uncommon as they should have been, and could either ‘brick’ the Mac or leave it stuck in a ‘boot loop’, repeatedly suffering kernel panics. These are now extremely rare.
The master tool for dealing with T2 firmware problems is Apple Configurator 2, free from the App Store. This should be used in the first instance to refresh iBridge firmware; if that fails, then a full restore should return the Mac to full working order. The difference between these is the extent of change in the Mac: refreshing merely installs the current version of iBridge firmware, leaving the contents of disk storage unaffected. A restore not only does that, but completely wipes and reformats the internal SSD.
Both procedures require a second Mac capable of running Configurator, and connection using a USB-C cable, as detailed fully in Configurator’s Help book. If you don’t have those, then an Apple store or authorised service provider should be able to do this for you.
Unlike Apple silicon Macs, T2 models can normally only refresh or restore the current iBridge firmware. Apple does leave an overlap period of seven days during which both the previous version of iBridge and a newly released version remain validly signed, but once that has expired there’s no way to downgrade T2 firmware.
T2 models also can’t by default boot from an external bootable disk, and that has to be enabled in Startup Security Utility, in Recovery Mode, beforehand. This limits disaster recovery unless you plan in advance, but refresh or restore should be curative.
In the early days of M1 Macs, they too had a disturbing tendency to run into firmware problems, but are probably more reliable now than either type of Intel Mac. They’re also by far the most versatile in that you can downgrade their firmware if you wish. This is important as Apple silicon Macs can only boot from their internal SSD; later in the boot process they can load and boot from external disks, but their firmware is always loaded from internal storage.
As with T2 Macs, Apple Configurator 2 is the key tool for similar processes of refreshing the firmware, or completely restoring the firmware and internal SSD to as-new condition. This doesn’t require a second Apple silicon Mac, and can readily be performed using an Intel Mac, provided that it can run Configurator, and is connected via a compatible USB-C cable, as detailed in the Help book. The fallback is an Apple store or service provider.
Configurator uses an IPSW image file from which to extract the firmware and software it installs. If you just want the current versions, then the app will download the latest release image. To downgrade, or install a specific version of macOS, download the appropriate IPSW selected from those listed by Mr. Macintosh. Unlike T2 firmware, Apple allows these to be used long after they were current, right back to macOS 11.0.1 at present.
Refreshing an Apple silicon Mac’s firmware is quick, simple and normally very effective, without any loss of data, provided that you have access to a second Mac and cable.
Studio Display firmware updates are normally offered in Software Update after you’ve installed the matching macOS update. They’re almost as nerve-racking as T2 firmware updates in that your Mac plays dead for an interminable length of time, with a black screen and no apparent sign of life. Much of the rest of the process is accompanied by an informative message on the display, or by the signature ellipsis or three dots.
If something goes wrong, all you can do is wait for another 15 minutes, with your Studio Display connected to your Mac, and your Mac connected to the internet. Whatever you do, don’t disconnect them, or restart your Mac.
There are two warning signs: a symbol showing a small padlock on a display icon, or the display showing black for over 15 minutes. Apple’s advice then is to unplug the Thunderbolt cable from the display and your Mac, then plug the cable back in again.
If that doesn’t enable the update to complete, the best way out is using a Mac with another display. That could be the same Mac (such as a Mac Studio) with a second display connected, or a notebook with its own built-in display. Start that Mac up (or restart it) with both displays active, so you can log in on the second or internal display. Leave the Mac for at least 15 minutes with a good internet connection, to allow the Mac to update the Display firmware.
If you don’t have access to a second display, or your Studio Display still won’t update, then contact Apple Support.
Problems updating firmware are very rare. When they do happen, don’t try aborting the update by forcing your Mac to shut down or restart, or even worse turning the power off. Keep calm and follow the recovery procedure: it’s very likely to work where panic will only make the problem worse.