Is that her back or belly? It sounds like she may still be in shock. I would keep trying to get some fluids into her, and maybe try some watery chicken feed and scrambled egg bits. Staying in a quiet area would be good for the time being. Let us know what she is like in the morning.
Sorry about your hen. Sometimes pictures of wounds and the chicken can help us see what you are seeing. Is she able to stand and walk, or is she down? Shock is common in the first day, and electrolytes or sugar water can help revive them. Is she be
breathing normally or is she having labored...