Hello,
I am Sumit here to assist you with this question.
CMD.exe is not a standalone file - it requires DLLs, and some other executables to run. Probably some files that are required got modified in an unrecoverable way in recovering Windows.
This is why Microsoft does not recommend what the user did in the Video.
Please set up a PIN first so you do not get locked out as step 1.
Second
Try doing a repair install. A repair Install keeps everything including Files and applications and reinstalls Windows.
How to Repair Install Windows 10
http://www.yourwindowsguide.com/2016/06/how-to-...
Repair Install Windows with an InPlace Upgracde
http://www.tenforums.com/tutorials/16397-repair...
The best and the easiest way is to use first method in the first article.
Standard 3rd party link disclaimer:
There may be links to non-Microsoft websites that would provide accurate and safe information. Watch out for ads on the websites which are frequently classified as a PUP (Potentially Unwanted Products). There is no need to buy paid products to fix your computers as they do more harm than good sometimes.