So first - huge kudos to Dell for being responsive.  They reached out to me right away and provided me with a viable solution. I think the latest Intel UHD video driver is busted (it's version number 30.0.101.1191 or higher).  I don't think the BIOS update has anything to do with it.  In my case, it was probably just the reboot to install that update that caused Windows to switch over to using the new Intel video driver. You may be able to get the screen to work temporarily by cold booting the machine and going into the BIOS (hold F2 at start).  Exit the BIOS without making changes and boot into Windows.  Go to the Device Manager and uninstall the Intel UHD graphics device.  Select the option to remove the driver as well.  Once this has completed, reboot the machine. Mine reverted to Intel UHD driver version 27.20.100.9664, and all is well again.  Hope this works for you (and perhaps others) as well! Thanks, Uthay at Dell!
After a recent video driver update my Dell XPS 17, after siwtching off the monitor to save energy, displays a completly distored picture when the screen comes back on after you move the mouse to wake up the monitor. Only long pressing the power button brings back "normal" operation or a reboot. This is very anonying as more often then not you can not recover from this and need to reboot. Please fix asap
Dell XPS 9710 video distorted