Hang during update to 15.3.1

This morning, I started the update of my M4 Pro Mac Mini from MacOS 15.3 to 15.3.1. It seemed to progress fine after I entered my system's admin password.

At some point I left the room for quite a while. When I returned, there was nothing on the screen, all black, and the system didn't respond to keyboard or mouse input. I waited a while longer, but still nothing.

I've done enough MacOS updates to know this was well past the point at which an update should have finished. Finally, I tried a quick push on the power button. Nothing. I pushed and held for a couple seconds. Still nothing. Finally pushed and held the power button for a long while then released. After that the system booted. I checked About in Settings and the update to 15.3.1 appeared to have finished successfully, but WOW not a good user experience.

I've worked on operating systems for Apple (A/UX in the 90s), SGI (IRIX), and Microsoft (multiple). OS update hangs like this are hard for an engineering team to detect without the right telemetry instrumentation, and usually the sign of some kind of lurking gnarly update bug.

Have others in the community experienced this?

Apple Support: Do you know if the engineering team has eyes on this issue? Is there log info on the system, or anything else which might be useful in root causing this?