ever wonder trying sfc/scannow or dism command, and still seeing all kind of errors even invoking the command or in the process of running it. under such circumstances, a reinstallation is required. fortunately, windows 10 installation is short and sweet. quoted an example below:
https://mikemstech.blogspot.com/2011/12/how-to-perform-offline-system-integrity.html
my personal preference: ” With any luck the system will boot correctly after this point and repair operations can continue. If the system is still unbootable, it may be necessary to perform an in place upgrade or rescue the files and reformat the system. “
i also noted that with the later versions of windows 10 installer, repairing system files from boot disk is getting more and more crankier. it seems that microsoft doesn’t like the idea of users repairing the system files, i can think of maybe for security reasons.