Windows 8.1 absolutely broken - can't repair, refresh, reset & upgrade

I've recently started to notice problems in Windows 8.1, when I couldn't launch my Visual Studio 2015. Being totally fed up with that, I decided to reinstall windows. (problem with VS was unrepairable failure in PresentationFramework.dll, so probably the .NET Framework as a whole).

But now, I can't reinstall Windows. I tried a refresh first, didn't work. Then a reset, did not do anything either. Then I decided I would try upgrading to Windows 10. Also failed for no apparent reason. I am aware that there are some bugs for people that upgraded from Windows 8, which makes them unable to refresh and reset windows. I also tried a reinstall from the pre startup/BIOS of the manufacturer, again, no luck.

I ran sfc /scannow to verify if any core system files are damaged/corrupted, but I get the following error message:

C:\windows\system32>sfc /scannow

Beginning system scan.  This process will take some time.

Beginning verification phase of system scan.
Verification 100% complete.

Windows Resource Protection could not perform the requested operation.

C:\windows\system32>

I ran it from an elevated command prompt. Also, ran it from the administrator account.

Full CBS.LOG can be found here In the file, this line stands out:

2016-10-24 20:17:17, Error                 CSI    00007110@2016/10/24:18:17:17.610 (F) base\wcp\sil\merged\ntu\ntsystem.cpp(2155): Error STATUS_FILE_CORRUPT_ERROR originated in function Windows::Rtl::SystemImplementation::DirectFileSystemProvider::SysCreateFile expression: (null)
[gle=0x80004005]

After this, the sfc pretty much brakes down and stops.

I'm not a windows guru, so I cannot think of any more solutions.

1. Salvage any data on the disk by putting it in an external HDD enclosure or installing it as a secondary drive in another PC.

2. Note the partition structure of the disk using the Windows Disk Management tool or an alternative. Find the Windows Product Key. There are tools to help, if you do not have the key.

3. Format the Windows partition.

4. Download the full Windows 8.1 ISO and create installation media.

5. After installing and activating 8.1, you should be able to reinstall your software and files, or upgrade to 10 and then reinstall everything.