As the day wore on, it became apparent that the chick couldn't balance; she would twist her neck up and arch back, and couldn't stay on her feet at all. Researching that, I landed on wry neck and gave her some Vit E and selenium and chick electrolyte water last night. At 1:30am, she was sitting on her belly instead of laying on her side. This morning she was standing!! As the morning wore on, I decided to put her in the brooder with the other chicks, hoping she would start to eat at their example. She was holding her own, for sure! So encouraging. I spent a lot of the morning in there with them, watching and making sure she wasn't in distress. Feeling confident, I left them for an hour or so, and when I came back she was sleeping underneath the Brisea heater but not very responsive. It was clear that the spunk I'd seen from the beginning while handling her was gone. I placed her back in the incubator thinking maybe she needed warmth or quiet, and she went downhill fast. A few minutes later she passed on. It was such a high morning, and then such a sudden crash. I'm sure I made errors along the way, but even my very bird-experienced sister was surprised. Thank you for your help. I'm glad I gave her a chance, but I guess it was just not meant to be.