Never ever upgrade OS without :
- Backup important files (better sync it to cloud every work hour)
- Unplug all devices or accessories from all USB ports
- Plugged in power cable
Yesterday, I upgraded macOS to another version when plugged to the USB-C hub (HDMI external screen, USB keyboard, USB for LED light). Then it restarted few times and hang with black screen. After waiting 10 mins nothing changes, I power off the macbook hard way (by hold power button). Then I never can boot it again (even to Recovery mode).
After researching whole Internet (Google, MacForum, Youtube) and trying 42 times, I failed to revive it! :(
But, keep searching I found my life saver's blog post , now I can restore the Macbook and reinstall clean MacOS Sonoma.
Thanks GOD :D
Btw, never stupid like me ! And if the thing works fine, keep it works ! If not, carefully upgrade it and always have a plan B.