I am almost certain that the obstruction is at the very top of her airway in her voice box (larynx). That's probably what you feel. That's all the maneuvers for tonight. Tomorrow when you have a helper, in addition to shining a light down her throat and snapping a good photo, I'd like to see you repeat the inverted maneuver without the thrusts, but have your helper stroke the hens' throat toward her beak just behind where her lower beak starts. That's where her larynx is.
You could try it alone by holding her body between your knees. It would be more comfortable for you to be sitting down. Then try a little circular massage of her larynx with a downward stroke to finish. Then that will have to be it until you get help tomorrow with photographing her throat. We may even be able to see what's stuck there.