I recently upgraded from Fedora 29 to 30 using dnf on the command line:
sudo dnf upgrade --refresh
sudo dnf system-upgrade download --releasever=30
sudo dnf system-upgrade reboot
All seemed fine, but something went wrong somewhere…
Boot sequence gets stuck on “Starting Load/Save Screen Backlight Brightness of backlight:intel_backlight” for 30+ minutes! Not sure for how long exactly; I left it over night and the machine was booted next morning, but so slow that it is not usable in graphics mode. Mouse cannot even move in real time… 
Booting the Rescue kernel 30 works fine and the system runs as expected, but the normal 5.3.6-200.fc.30.x86_64 30 kernel is not healthy.
Any suggestions on how to troubleshoot?
Or do I just clean install?