[NAME] I solved the problem by running BIOS recovery (and in the process I also figured out what the flashing lights mean, check out this doc: [URL]#2014_Present). The recovery process is somewhat finicky, but works well. This process has successfully updated BIOS to 2.17. Let me know if this works for you.
I tried every method I could think of: ran the manually downloaded executable from within Windows 11 beta, ran the executable from within a fresh install of Windows 10, through Windows Update, and running the update from within BIOS itself off of a USB device. SupportAssist scan doesn't prompt to update the BIOS, so couldn't try that. Everything starts as expected, I get a prompt to allow suspension of Bitlocker, and the laptop restarts. For a split second under the Dell circle logo I see a message "Please wait while we're updating the system BIOS" (or something similar) and then the laptop restarts again and boots straight into the OS. Very frustrating. I can't find any information from Dell (not surprising).  Any thoughts?
XPS 13 9365 BIOS 2.17 update fails