Repair install from a secondary drive

[GreenSnail]

My primary installation of Windows 10 has become corrupt and will not boot. Neither DISM nor sfc can repair it yielding various errors (1392 and 50 for DISM and sfc says the system is unable to complete the process). In my desperate plea to not have to reinstall windows and then every other program on my computer to resume working I came across the option to do a repair install. With previous versions of Windows this was my go to if all else fails but the option in Windows 10 is not nearly as straightforward.

The gist of my question is: How do I do a repair install on my primary installation of Windows from a secondary installation of Windows (as the first installation will not boot)?

 

[GreenSnail]

To clarify the BSOD error code is 0xc000021a. I can provide the DISM log if that helps at all.