Happy to report the issue is fixed! Dell support suggested upgrading the BIOS v1.19 again.  I tried and it was a success.  Logs from Dell Command | Upgrade showed the initial BIOS v1.19 upgrade on 11/8 failed with 3 errors.  That was likely the cause of the laptop screen to malfunction.
Finally relented to Dell Command | Update's notifications and updated BIOS to v1.19 on my Precision 7760 (Intel Xeon W-10885M), along with Windows (10) Update.  Initially okay, but after reboot the laptop screen went dark (no power, no backlight bleed, no POST, nothing).  Through an external monitor, I saw Device Manager not registering a Monitor connected to the internal video driver (Intel(R) UHD Graphics P630), as if there was no laptop screen at all. After many hours of diagnosing, finally downgraded to BIOS v1.18, v1.17, then back to v1.18 (without laptop screen, unable to observe the progress of BIOS flash, thus repeated a few times).  Eventually got the screen back, with the laptop showing BIOS v1.18. In case anyone else runs into this problem.  Downgrade to BIOS v1.18, reboot and leave the laptop alone for 10 minutes to flash BIOS and various firmware. I also disabled Dell Command | Update automatic update check for now.
Precision 7760 BIOS 1.19 - Breaks Laptop Screen WARNING!!!