Since you suspect your hen is eggbound, I recommend you soak her in warm water like you were doing. Gently massage her underside for about 10-15 minutes. Then wear a plastic glove and lube your fingers with olive oil. Insert well lubed finger in her vent to feel for any obstructions. Lube the inside and outside her vent with olive oil. The warm water will expand her innards and the olive oil will make it easier to lay the egg. There's another possibility; you stated she's acting lethargic...I recommend you check her poop for worms. Good luck.