Yikes! It doesn't look as bad as the first couple of pix (less swollen/distended), unless it's just the viewing angle. It might pop back in on its own, or as a last resort, you could sedate the fish (MS-222/finquel) and try to pop it back into place.
At this point, I'd just keep an eye on it, as lions can go a good while without eating.
FWIW, our volitans smacked herself against a rock chasing a crayfish, and her jaw was a little tweaked for a few days, but it was fine after it healed up.