(1) You should make the Windows system image backup (as I posted on page 4), so that you can get back to your current state, in case things get worse. The last few I made took well under 15 minutes.
(a) If you do a clean install, only the system image can bring you back (if necessary).
(b) If you do an upgrade/repair-install, you do get an option to "go back to previous version", but it only lasts ten days.
(2) I don't like the looks of the following...
"After reset and pressing F12, brings up the "startup device preference" for which
USB HDD:SANDISK, PARTITION 1
>>UEFI: SANDISK, PARTITION 1
Is selected"
(a) You meant "restart" (reboot), not "reset" which is like a clean install. OK.
(b) Why does it say "HDD"?
(c) Why does it say "Partition 1"?
(d) What was plugged in?
Your Disk Management showed this...
That looks fine, but I think Rufus must have done something wrong for F12 to think it has more than one partition & that it is an HDD. You should make your Installation USB flash drive directly from the MediaCreationTool to the USB drive instead of using Rufus & an ISO, as Igor Leyko said. Or speak to Slance310 on how to use Rufus right, I don't know.
Then, always boot it with the UEFI option. That means F12 for you. But it has to look better than what Rufus did. It should just say just: "UEFI: SANDISK". And the Windows Boot Manager must be the first item to boot in BIOS setup (as Slance310 said) -- not the USB drive or anything else.
If it fails to boot, then try turning off Secure Boot &/or Fast Boot in BIOS, as the others said. But turn at least Secure Boot back on afterward, as that is a major advantage of your UEFI installation. It protects against root kit viruses.
(3) But I think you should try an upgrade-install from a USB flash drive. Sometimes it works better that way than taking it from Windows Update. Make it here...
https://www.microsoft.com/en-us/software-download/windows10
Download Windows 10 - This is always the latest finalized Windows version, currently 2004.
As Igor Leyko said, download MediaCreationTool2004.exe & run it to make a Windows 10 Installation USB flash drive. Follow the instructions under "Using the tool to create installation media". As it says, match it to the Language, & Architecture (x64/64-bit or x86/32-bit) of the computer on which it will be used. The Windows Edition to take is "Windows 10", which includes both Home & Pro. That is all prefilled, if the tool is run on the computer in question. Instructions are at the site how to use it to do an upgrade. Basically, you boot to Windows, plug in the media, open it in File Explorer, & click Setup.exe. It may work better this way.
But, if it fails, let us see
SetupDiag
Show us the full contents of SetupDiagResults.log. It should be small enough.
(4) "Under startup the current settings are:
CSM - DISABLED
BOOT MODE - UEFI ONLY
BOOT UP NUM LOCK STATUS - ON
If I change CSM to ENABLED then:
BOOT MODE has the option of: AUTO, UEFI ONLY or LEGACY ONLY
(NEW OPTION) BOOT PRIORITY: UEFI 1ST or LEGACY FIRST
BOOT UP NUM LOCK STATUS - ON"
You've definitely got the superior UEFI installation (I saw your EFI). So, I would leave that alone. CSM is for Legacy.