Monterey update/iMac/won't reboot
After receiving notice that Monterey was available, I confirmed that it was appropriate for my iMac Intel 27 in 5G late 2015. Though I once had a horrible problem with an OS update on my MacBook Pro, I went ahead and downloaded and began installing the Monterey update on my desktop. And so I set in motion the baffling cycle of frozen reboots. As others have described, I would get part way through the phony 28-minutes left notices (does that actually mean anything at all?) and get down to "less than a minute left though the progress bar had hardly moved after the first third of the way. After hours of waiting for the "less than a minute," I tried rebooting, tried rebooting in safe mode (the machine just kept trying to restart again and again), tried rebooting in recovery mode (my cursor was frozen so I couldn't choose any of the options), tried resetting SMC and NVRAM to fix the cursor, tried each of these possibilities several times...nothing.
Right now, my desktop is trying to reboot itself in the other room. Every few minutes I hear it restart. Clearly, there's something very wrong with the install.
So, I'm at a loss as to how I go about getting back to some semblance of a normal, functional computer. I don't care if I ever get to use Monterey, but just get me back my machine running Big Sur like I had at the beginning of this. Is that even a possibility?
Help.
iMac 27″, OS X 10.11
