I did my weekly patches this afternoon, and this time the system booted up fine. So
I'm back to what caused the problems.
* Motherboard battery? Quite unlikely, but not 100% certain. Battery replaced anyway.
* Hard drive? Somewhat unlikely. Two 4-hour non-destructive disk checks found no issues.
System cleaned; cables dis- and re-connected; hard drive removed and put back in; no
kinky cables seen. Destructive testing and replacing the hard drive are not options for
me at this time. Circumstances suggest such would be over-kill.
* Somehow caused by the "dnf upgrade"? I can't assess this. After the
second failure (May 25), I backed up all user data, and then upgraded from f24 to f25. I
did not see any problems. This afternoon's patches were f25; the failures were f24.
So I can no longer test whether f24 patching is at fault. But if it were, I'd be
surprised if I were the only person to be hit by it. So my leaning is that it wasn't
the patching that caused the problems.
* Power supply? Somewhat unlikely. I know of no way to test this. But Tim's
analysis and other circumstances suggest it's not worth pursuing this possibility any
further.
Two questions:
1. Are there any other theories I should consider?
2. Should I submit a bugzilla? (If yes, against what?)
thanks,
Bill.