Baby chick chirping with eyes closed

Hi all, although I've had chickens for four years I've never actually raised chicks in a brooder until now. A couple of days ago I tried to put some three day-old chicks under a broody hen but she wasn't having it! The four chicks were chilled and in shock so I warmed them up and they recovered. They're now inside doing very well, but one chick is acting strangely. She's a tiny Dutch bantam chick and all she does is stand, eyes closed, chirping LOUDLY (the sound chicks make when removed from their mother). She runs around and seems in good health but isn't eating or drinking (unless I tip her beak into the water) and all she does is chirp. I'm worried she'll become weak. What could be the problem and how can I help her? Thanks xxx

Chances are this chick lost more body heat than the others due to her small size, and now she's suffering stress from it. Rig up a heating pad on the low setting, make a little tent out of it and let her snuggle up to the warmth. Also, give her a drop of undiluted Poultry Nutri-drench and make a weaker solution for her water. Perhaps she needs a little extra care to recover.

I wish I could but it's past midnight where I am (Europe) and I have neither of those things. Tried more sugar water but either she's sleepy or fading because she's cheeping less and I think perhaps a little weaker. I don't know what else to do... Hot water bottle?

A small chick, peeping constantly, acting lethargic, needs extra heat so a hot water bottle would be fine. place it under some soft towels and be sure the water bottle isn't so hot as to burn the chick. Keep up the sugar water.

IDK what was wrong with them, but all but one died. For some reason, that batch of chicks was sick. The only one who survived was the healthy one of the bunch. I don't think it's the type of chicken bc I recently adopted some more stripy butt chicks and they're doing just fine. I wish I could have done more for them, but at least they're in a better place now. Thank you for all of your help.