Trying (unsuccessfully) to repair Windows Security. Anyone kindly help me?

I have been trying to repair the Windows Security app for some months now (on and off!), following advice in threads I find online, but with no success. When I open the app, all I get it a black window with the app shield logo in the middle.. Has anyone any suggestions? This is what I have done:

In Settings, I tried to repair and then, when that didn't help, reset the app (got a 'tick' next to the options after a little while, so I assume it all worked), but still when I open Windows Security all I get is that black window with the app logo .. nothing happens.

I had also tried the same via Powershell, with this, by the way:
Get-AppxPackage Microsoft.Windows.SecHealthUI | Reset-AppxPackage

Then I tried to reinstall and re-register Windows Security via Command Prompt (as admin.):
C:\>PowerShell -ExecutionPolicy Unrestricted -Command "& {$manifest = (Get-AppxPackage Microsoft.Windows.SecHealthUI).InstallLocation + '\AppxManifest.xml' ; Add-AppxPackage -DisableDevelopmentMode -Register $manifest}"

This ran, producing this:
Add-AppxPackage : Cannot find path 'C:\AppxManifest.xml' because it does not exist.
At line:1 char:104
+ ... fest.xml' ; Add-AppxPackage -DisableDevelopmentMode -Register $manife ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (C:\AppxManifest.xml:String) [Add-AppxPackage], ItemNotFoundException
+ FullyQualifiedErrorId : PathNotFound,Microsoft.Windows.Appx.PackageManager.Commands.AddAppxPackageCommand

I tried SFC, running Deployment Image Servicing and Management tool first. Unfortunately, DISM stops at about 58% with "system cannot find the path specified". Just one failure after another!! I attach the DISM log.

I ran scannow /sfc anyway, in spite of DISM failing to complete - no problems were reported. Of course, after a reboot, Windows Security is still as before.

About ready to admit defeat!!

Thanks.

Have you tried?

@martinlest


Here's ten points, just for filling out your computer specs.


I would just do an In-Place Upgrade (repair install).
It fixes Windows problems and you won't lose anything.

Use Option Two, ISO method...

I second what Ghot said, except to add one other point. There is a possibility the repair install will fail, dependent on the corruptive state of your system. I would certainly either image the system or manually back up personal files just in case a reset or reinstall becomes necessary.