There should not be anything underground except a coupling. I would guess it has collapsed. But you pulled out the 6? Why not just use one of the 6's to pull the 4 back in as it comes out, or is it too late?
Collapsed is a good possibility too. I never discount the work or ideas someone had in the past that seemed like a good idea at the time. There is a light pole with an outlet on it and conduit going into the ground that is perpendicular to where I believe the blockage is at. Its what had me wondering if they did some sort of funky underground junction box or something. Anyway, I'm going to fish again from the opposite end to confirm that the blockage is in the same spot from both ends. That way if I do have to get in there and make a repair, at least I'll know where to dig.
I was going to attempt using the 6's to pull the 4's as a last resort in case they get stuck and I'm left without power to the barn.
I attempted to dig near the barn in the dirt to open up the conduit so I could bypass the three 90s at the barn but I was met with a large white corrugated pipe that runs directly over where the conduit is running. Had me scratching my head because I've never seen white corrugated pipe. I'm guessing it's for some old drainage system that's no longer used but who knows.