This is a list of fixes for the KB release. I am wondering if somewhere along the line Dell SA auto downloaded and installed the BIOS update. And this is really off the wall, if that download was synced to One Drive and then reinstalled during the MS update.

@ThomasLG 

Turning OFF pc while 5005101 is installing can crash windows to the BLACK SCREEN of Death.  Takes several hours sometimes to install.  Its better to download the almost 600 gig update and run it offline standalone. KB article numbers: KB5005101

More information:
https://support.microsoft.com/help/5005101

Support Url:
https://support.microsoft.com/help/5005101

6/15/21
IMPORTANT This release includes the Flash Removal Package. Taking this update will remove Adobe Flash from the machine. For more information, see the Update on Adobe Flash Player End of Support.

KB5005101 is  a preview update and the final version is going to be released in the form of the September Update

My 2 cents :

1) never install preview updates , because being a test subject is not a good thing

2) pause entirely updates until askwoody  gives the green light to install ( this means delay the monthly updates by 24/25 days and let others be the test subjects for the standard updates )

PS @ThomasLG , which precision workstation do you own ? (so that I can put a manual note here about the specific bios update, in case)

Hi, @speedstep.  I didn't turn the PC off -- it downloaded the update, installed it, and said it needed to reboot.  I let it, and when it was going to come up, I got the dreaded 2-6 LED code.  Something in the Windows update (or something ELSE that got done) messed things up.  I didn't let Dell's software do the update; I did it from Windows Update.  After the 2-6 code, I DID turn it off, but by then, the damage was done.

Dell Support Assist and or Dell Command downloaded and tried to install a Bios update first.

Hi, @mazzinia.  It's a Precision 5820, i9.  I have it pretty well loaded up -- 32 GB RAM, three 4-TB drives in RAID 5, Dell's 4400 GPU driving a 32:9 monitor, a cheap second GPU for the other two screens, a TV tuner (I'm digitizing some old VHS tapes), and my M.2 NVMe drive is on a PCIe x16 card.

When I first purchased it, the unit was DOA, but it sat around the house more than 30 days before I unboxed it, so I went around and around with Dell to get a new unit as a replacement, rather than a refurb.  The new one worked great.  Until I attempted a "critical" BIOS update, which bricked it.  Then it worked great for another three weeks until THIS update, which bricked it.  I'm vewwy vewwy gun-shy at this point!

Hey, Dell,  I hope you're monitoring these forums.  

I'm about to get my third motherboard for a 5820T in 7 months.  I called last Sunday.  Yes, I realize it was a weekend day, and that the next day was a US Federal holiday.  I expected the part to be dispatched Tuesday, and service was originally scheduled for Wednesday. As frustrating as "Sunday to Wednesday" was, I understood, and was prepared for it.

Then Wednesday came and went, and I was told there was a problem with the shipping carrier, and that the technician didn't have the part.  So I was rescheduled for Thursday.  Thursday came and went, and I was re-scheduled for Friday. Now Friday has come and gone, and no part, and no technician.  I called WWTS's 866 number and got their "central switchboard" (with toddlers screaming in the background), and was told that the part HAD arrived yesterday, but that they're experiencing "higher than normal volume", and my service has been delayed until Monday.  

This is an utterly unacceptable level of service.  I chose to go with Dell, rather than spec components and build my own, largely because of the warranty. I felt that even if something DID go wrong, I wouldn't be down for more than a couple of days.  After all, Dell is standing behind it.

Now it's going to take me 8 days to get a mobo replaced for the second time.  If they don't push me from Monday to Tuesday.  Or Wednesday.  Not a happy camper.