MacBook Pro 13" 2019: T2 Chip Boot Loop
What Happened
Had an accountant from Pennant Hills bring this one in. Their MacBook Pro 13 had been updating to macOS Ventura when the power went out or something, she wasnt sure exactly what happened. After that it wouldnt boot properly. Would show the Apple logo for a few seconds then just shut down. Over and over, stuck in a loop.
Shed taken it to Apple and they said it probably needed a new logic board. $689. She wanted to know if there was another option because she had alot of work files on there that werent backed up. Financial stuff, client documents, that sort of thing.
What We Found
The 2019 MacBook Pros have this T2 security chip in them. Its basically a separate little computer inside the Mac that handles security stuff, encryption, and has its own operating system called BridgeOS. If BridgeOS gets corrupted the T2 wont let the Mac boot at all. It thinks somethings wrong with the system and blocks it.
Thats what happened here. The update got interrupted and the firmware on the T2 got messed up. Safe Mode wouldnt work, Recovery Mode wouldnt work, NVRAM reset didnt help. The Mac itself was fine, the hardware was fine, it was just the T2 firmware that was corrupted.
We put it into DFU mode which is a special mode that lets you bypass the T2s normal startup and connect to another Mac. Once we did that we could see the Mac showing up in Apple Configurator. That confirmed the T2 chip itself wasnt dead, just the firmware on it was corrupted. Hardware was good.
The Repair
With the Mac in DFU mode we used Apple Configurator to restore the T2 firmware. Theres two options, Revive which tries to fix the firmware without touching your data, and Restore which does a full wipe and reinstall.
Tried Revive first. It downloaded fresh BridgeOS firmware from Apples servers and pushed it to the T2. After that the Mac actually booted into Recovery Mode which it wouldnt do before. Progress. But the macOS installation itself was also damaged from the interrupted update so it still wouldnt boot properly into the normal desktop.
So we used Restore next. This reinstalls both BridgeOS and macOS but keeps the user data partition separate. The restore took maybe 45 minutes and when it finished the Mac booted up to the setup screen.
Logged in with her password and everything was there. Documents, Desktop, Downloads, all her accounting files. Applications needed reinstalling because they were on the system partition but all the actual data was intact. The T2 encryption meant her files were still protected throughout the process.
Result
Got her Mac back to her the same afternoon. All her client files were there, nothing lost. Apple wanted $689 for a new logic board and that wouldve wiped everything anyway. This was a firmware issue not a hardware issue. Didnt need any parts at all.
Notes
T2 boot loops after failed updates are actually pretty common. We see a few of these every month. The Mac looks completely dead but its usually just the firmware thats corrupted not the actual hardware. DFU mode and Apple Configurator can fix most of them without any parts.
The tricky bit is that Apple Store staff dont always check for this. They run their diagnostics, it fails, and they quote for a new board. But if you can get the Mac into DFU mode and it shows up in Configurator then the T2 is working and you can usually restore it.
MacBook Stuck in Boot Loop
If your MacBooks keeps restarting or wont get past the Apple logo bring it into the workshop. Alot of these are firmware issues not hardware problems.