My MacBook Pro was bricked after installing macOS 15.6.1 update.
It never restarted. Appeared to be completely dead.
However I found I could get it to boot after disconnecting the battery.
It would boot to the login screen, then after a few minutes, with the progress bar at about 50% it would crash.
I could put it target disk mode and copy off the files I needed to keep.
But it would not boot into safe mode, or recovery.
I have a Bootcamp partition on it, and using the Option key at startup I could boot into Windows and that seemed to be working OK.
I tried a USB bootable installer, but while it appeared as a startup option, the MacBook would not run it (probably because the boot from external drive security setting is OFF – I have no memory of changing that setting).
I could not boot into recovery mode.
I guessed that my battery (500 cycles) failed during the 15.6.1 update (I was not on power at the time – my bad) and maybe the firmware could be damaged.
I managed to get it into DFU mode and erased the drive and restored the firmware, but step 4 of 4, installing the system, failed with a timeout.
I can boot into internet recovery – indeed it only boots into internet recovery now.
I am using ethernet connection (via Ethernet to USB-C adapter), and eventually the progress bar appears and slowly advances to about 5mm, and then stops. The time to complete install shows as 24 hours, but 24 hours later it still hasn’t moved a millimetre more.
Any clues/suggestions as to how I can get out of this hole?
