Windows 8.1 black screen with cursor, no safe mode, sfc not working

I'm trying to repair my computer from booting into a blackscreen through the CMD mode (safe mode isn't working), after seeing that Startup Repair couldn't repair my PC. When I type sfc /scannow, I get the following message:

There is a system repair pending which requires reboot to complete. Restart Windows and run sfc again.

So I tried running sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows and after around a minute of waiting since the sfc began, this message appears:

Windows Resource Protection could not perform the requested operation.

I cannot simply "reboot" to get rid of that pending repair because I'm stuck in a blackscreen with only my cursor appearing and nothing responding, not even Ctrl+Alt+Delete. I would need to reboot straight into the recovery menu, but I have no idea how to do that. Switching to integrated graphics or going into a safe mode does not get me past the blackscreen. I also tried a chkdsk which found no errors.

Then I tried doing a dism /online /cleanup-image /restorehealth which told me that the component store corruption was repaired. However, I heard it still requires a reboot to fix sfc, and after restarting twice during the Windows boot logo and then getting into recovery options again, I'm getting that restart pending message again when running sfc /scannow. The dism /image:C:\ /cleanup-image /revertpendingactions requires a reboot too, so it's of no use here, unless I can reboot directly into the recovery menu. I found a pending.xml file under X:\Windows\WinSxS (not under C:) which I deleted and successfully ran sfc /scannow afterwards, but after reaching 100% I was left with the Windows Resource Protection message again, same as with the offline parameters.

Another suggestion I found was to try ICACLS C:\Windows\winsxs, which tells me that it successfully processed 1 file and failed processing 0 files, but that does not change anything on sfc.

As a last option I tried reverting to two of my images automatically created yesterday and two days ago, but each gave me this error:

System restore failed to extract the original copy of the directory from the restore point. Source: %ProgramFiles%\WindowsApps Destination: AppxStaging An unspecified error occured during System Restore. (0x80070057)

Here is my CBS.log And my SrtTrail

For information, the blackscreen problem started suddenly after I left my computer running through the night to finish some downloading (not installing anything), but it's possible that a BSOD occured during the time, which I am getting at least once a week these days (for numerous errors that I'm never able to fix)

Edit: Just finished downloading and creating a bootable recovery DVD, tried the above steps through it but it doesn't seem to be any different.