I have a month-old iMac with the M1 chip. Beautiful machine. That is, until last Thursday night. All of a sudden the screen went dark. I tried to restart several times before it finally restarted. Upon restart, there was the dock on the bottom, the menu bar at the top and nothing in between. Just the gray desktop with nothing on it. I could use the things in the dock, but they all operated rather haphazardly. The first thing that I actually got running was Apple music. After several hours, icons finally appeared on my desktop. They disappeared again for a while the next day.
Since then, everything seems to be working, but very slowly. Especially online. Googling something or getting into a site can take 10-15 minutes. It took me a couple of hours to launch Photoshop. No matter what I do, all I see is that damn spinning disc.
Ok, I contacted Apple support and chatted with a guy there. He didn’t understand what happened any more than I do (he said the situation “isn’t ideal”). So we made an appointment tomorrow at my local Apple store. Maybe one of their “geniuses” can figure it out.
As a first guess, I’d say check the SSD, given that many of your symptoms seem I/O related. But given what little experience I have with the M1 Macs, that’s no better than an educated guess.
My best guess (which, I’ll be honest, is not that good) is that the SSD hardware failed in some way that critical system files were readable, but only really slowly. The OS/SSD firmware eventually managed to get everything off the bad part and/or reconstruct whatever metadata was lost. Curious to hear what the Apple people say.
Well, I’ll be picking up my iMac tomorrow morning. When I took it in, the “genius” couldn’t even get the start-up’s diagnostic to run. Since then, they were able to run a diagnostic which showed no problem in the hardware. That left a firmware/software problem. I told them that the only software I’ve used has been either the Apple software that came with the computer or up-to-date Adobe software, so that narrowed it down to a firmware problem that happened when “migrating” files from my old Mac. So they basically wiped everything clean with a DFU restore, and I’ll have to re-transfer everything via an external drive.