You don't turn those bolts with the two flat slides. Leave the nut on the end and smack it back that way. The bolt itself is splined, so you don't want to turn those flat sided bolts. Just smack and wiggle the knuckle.

Or... find something long that you can keep pressure on to pop the joint. I used to put my feet on my 4 foot or less jack handle that I put in there. Yes..I was laying on the ground to hit the joint with my normal sized feet on the bar to slightly push down on it.