Chickens can be very stoic about tolerating pain. How are your others doing? Do they go out and roam around, or are they pretty much confined to a coop and run? Have you thought about placing her in a wire dog crate near the other chicks to visit? It would be interesting to see how she reacts to...
The green poop may be from not eating. Have you ever had any chickens that died from an unknown cause or who had suffered paralysis in one or both legs or wings? I really hope that your pullet is not suffering from Mareks, but I would try to get her to eat and drink. Mareks would need to be...
I would try to lift her occasionally to see if she can stand or move legs. Keep up the electrolyte water and food. Think about making a chick chair or sling which can get her upright to eat and drink:
https://www.backyardchickens.com/threads/versions-of-chick-chairs-please.1166308/
She could have dehydration if her legs were not working well yesterday while it was hot. Mareks is the most obvious possibility if she will not move her legs. An injury might also be a possibility. Some chicks become very weak with coccidiosis. How are her poops? Botulism usually causes flaccid...