Hiya, and welcome to BYC!
Sorry about that lethargic one not making it. 
If you need any tips for now or the next few weeks, this article might be helpful for you.
https://www.backyardchickens.com/articles/brooding-chicks-the-first-6-weeks.74640/


If you need any tips for now or the next few weeks, this article might be helpful for you.
https://www.backyardchickens.com/articles/brooding-chicks-the-first-6-weeks.74640/