how to check for unfixed corruption after file system fail?

[Moogle Stiltzkin]

powercut resulted in check file system.

so after running the check file system from qts, what is the command to put into sftp putty in order to check if any file was corrupted if any ?

if i recall right any problematic files would then be output to lost&found folder

is there some sort of command i should use?

[MrVideo]

I'm surprised you do not have the NAS attached to a UPS and configured to gracefully power down before the UPS battery goes flat.

The e2fsck/e2fsck_64 program will be the one that puts files into lost+found. And only then when the file can't be attached to a directory entry. Unfortunately the orphaned file will not have its original file name. You'll have to figure that out.