Hi William,
It does take a while. I'm not sure which command did you use, but it should be with spaces:
DISM.exe*<space>/Online<space>/Cleanup-image<space>*/Restorehealth
You should see a progress and a confirmation after its done. Refer to the photos below:
Also, make sure that you see the system32 in there. It indicates that you were running the command as administrator.
Let us know how it goes.