F24 black screen since libglvnd update this weekend

My Fedora 24 / KDE box with the nVidia drivers was working beautifully until libglvnd got updated on Saturday. After that, the screen would turn black when booting switched to graphical mode. I tried reinstalling the nVidia drivers but that did not help. I switched the display manager to lightDM and it's now possible to see the login screen, but logging in still gives a blank screen. Today saw a big update which brought in new xorg-x11-drv-nvidia*, new libglvnd*, and a ton of kf5* packages. I was very optimistic that this would bring the computer back into proper functionality. Sadly it did not. I have run nvidia-bug-report.sh but I can find nothing significant in the report log. At this point, I'd be grateful for any clues to help diagnose why it's failing - and delighted, of course, with a solution! Many thanks, Chris R.