Ok, after a week I fired up this WIN 10 Dell again, no problem.
Then I run Updates........
1-The usual security & .net etc.
2-A long 19009 update=KB4562900
3-Plus an SCSI update.
My problem started after I went to 1909, not directoly after, but the next long update some time afterwards-weeks.
Ok, so updates all finish downloading, some pending install, and reboot.
I reboot.....
1-On reboot, no bootable device, blue screen.
2-Try again, same thing, blue screen. No bootable device.
3-Try again, same thing, blue screen. No bootable device.
4-This time I press F2 go into BIOS, see nothing strange.
5-I exit BIOS.
6-It reboots and the following....
-Preparing Automatic Repair....Wait..
-Diagnosing your PC..Wait...
-Get updates it says....This then completes.
-It reboots, and load fully, no problems.
-I reboot 5 times, no problems.
7-I did an Update troubleshoot, it found problems and fixed them.
The PC further operates normally, no hint of a problem.
>>Update history of today confirm all these updates installed successfully.
I refuse to think my SSD drive is faulty, I would rather think it is a malfunction from Microsoft on how they apply changes on shutdown, & changes on the reboot thereafter like before these went well always, till after 1909.
Now I have a block of 180 days on major updates still active, I dont know if this choice mess with the 1909 feature updates...?
Build=18363.1016
WIN 1909 2020-03-01