shutdown /s /f /t 0
However, some people online seem to suggest that this might not be enough with Win 8.1 / Win10,
powercfg.exe /hibernate offinstead.
Googling any of the 2 aformentioned messages just leads me to (not really many actually) threads in regards to...
Windows' intrinsic weirdness / endless loops & eventually...full-reinstall.
"Windows is hibernated, refused to mount. Operation not permitted."
"Windows Preinstallation Environment does not support Hibernate."
...and more or less the same suggestions that have already been made above.
The only other things would be to also try running chkdsk, sfc /scannow etc etc...
Kinda doubt they'll do the trick, but you never know.
So if still nada after all the above, personally, i'd just bite the bullet, backup the files using a live stick, and format.