I think that error relates to the system being locked but as you were able to perform a chkdsk earlier, that may not be the case.
With the HDD in its own machine, boot up with the install media to go to the advanced boot options - select Command Prompt and enter bcdedit |find "osdevice" to see what it reports.
If it sees the volume then using that partition letter instead of the X I have exampled, enter -
sfc /scannow /offbootdir=X:\ /offwindir=X:\Windows
This cmd may or not run but for clarity, that is a Pipe symbol before find and is the uppercase of \ and note the spaces before each /
When you originally did the chkdsk and attempted the sfc /scannow, was the HDD in its own machine ?
If it sees the volume and the offboot sfc doesn't work, then you may have to go for a Reset which will keep personal stuff, but any programs will need to be reinstalled.