Focal Fossa installation issue

[American Bourne]

I don't know how exactly to file this bug or what to file it against.
Or if anyone one this list will even care; here goes anyway.

My Dell Inspiron 3847 runs UEFI w secure boot enabled. I downloaded
Xubuntu 20.04 today and began the installation. At the point where I
was prompted to Download updates while installing / Install 3rd party
drivers, I was forced _this is a a new step in the Ubiquity installer
for me_ to create a Secure Boot password, which I would enter after
the newly installed system restarted. I created and entered the
password; 3rd party drivers for the system's nVidia 8600 GT -
nvidia-340 - duly installed. The installation completed successfully
and I rebooted the system. After rebooting the system, there was no
visible POST or video. The system connects to a HP Compaq LA2405x
widescreen monitor via DVI. Going through monitor's menu, DVI input
was inactive. I rebooted 3 times, with the same result - no visible
POST, no ability to enter Dell BIOS to troubleshoot.
I removed the nVidia card, switched the cable output on the monitor to
the Dell's integrated VGA. At this point I had visible POST again and
I was able to enter Dell BIOS and disable Secure Boot. I shutdown,
reinstalled the video card and reconnected the DVI output. After doing
this, I once again had visible POST and boot from nVidia graphics on
the Xubuntu 20.04 system. I logged in, and starting composing this
email. So far, the system seems to be working well.
Thank you.

Rich Dennis