Checked the reservoirs each time for fluid and no dice
Maybe I'm misunderstanding what he said, but if he's seeing no fluid in the reservoirs then that should point to air in the lines (and not fluid).
No fluid, no pressure, no worky.
Again, I'm assuming (which is bad) that "no dice" means no fluid in the tanks.
Lets say that the system is only 25% full (random number) when he got the truck.
The reservoirs would be dry.
He tops off the reservoirs, and pumps for 20 minutes.
Nothing has changed, nothing would. It would still be mostly air in the lines.
The system is only 30% full now.
He's seeing no oil leaks. Expected. There's no pressure. Air is still in the majority of the system.
You bring up a valid point about a possible hose misconnected (we know someone prior mucked with it).
But if his tanks are dry after topping them off, he shouldn't just move on to the next troubleshooting point, IMO.
To me, dry tanks after topping them off indicates the system took that fluid in.
It needs more fluid.
He needs to bleed the system until the tanks are full and any air is removed.
That's when he'll likely see things start to move and likely discover the leak if one exists (once the system is fully bled of all air and pressure can build).
Again, I may be misunderstanding what he meant.
But if he's seeing a dry hole in each tank, he's not bled the air and IMO he should keep at it before tearing apart the pumps, rerouting hoses, etc.
edit: I'd maybe even focus on the tire lift first (bypass the the stuff that's not right there to watch). If he can get that working, then flip it to cab lift and see what happens