Ten days ago, I posted a problem and described it as "Intermittent Boot Failure". Having received no replies, I continued to work trying to solve my problem. At this point the boot failure is no longer intermittent. Shutting off the machine three times at start-up hardly ever seems to work.
During the ensuing time it was suggested that I create installation media using another computer and reinstalled Windows 10: DONE to a USB drive
Run Bootrec /fixmbr - DONE
Run Bootrec /fixboot - FAILED Element not found
Run Bootrec /scanos - DONE
Run Bootrec /rebuildbcd - DONE
Run ChkDsk - DONE. No drive errors were found
Powering while holding down the shift key, then choosing Troubleshoot, Advanced Options, Start-up repair yielded "Startup repair couldn't repair your PC.
Changing BIOS from Legacy to UEFI. DONE. Could no re-boot in UEFI so I have reverted to LEGACY.
Run two separate diagnostics from the DELL support screen. The second diagnostic purportedly found and fixed 26 problems.
Updated all drivers.
Updated BIOS to A14.
Despite all of the above, upon boot-up Windows 10 displays the Dell logo, then the Windows logo, followed by a white screen with a cursor and hangs there.
Hopefully this posting will elicit a response and a solution.