ok for now i'd leave testdisk alone.
i'd use photorec :- http://www.cgsecurit...g/wiki/PhotoRec or recuva :- https://www.piriform.com/recuva to search the drive for lost files and save them to your other drive, if neither can find any files then that will confirm my pessimism and the drive is wiped and empty with nothing you can do to save the data that was on it..
with luck though they willl find everything on the drive and copy the files to your other drive. once that is done it's then up to you if you want to continue trying to fix things with test disk, or simply just format the drive again and run some tests on it to see if it's failing and not worth risking your data on it again, or if it passes as ok then copy the files back to it.
Edited by terry1966, 25 August 2017 - 05:14 PM.