Welcome to BYC! So sorry for your loss. I remember how terrified I was when I got my first chickens and they were robust 8-12 week old ones. I was sure I would mess it up and I did. But I learned from my mistakes and then I got chicks and was sure I would kill them just by looking at them but they survived. And now I have chicks again and one is having a hard time.
Chickens have been a bit of an emotional roller-coaster for me. But there is nothing like the high of the first egg, or the first time that chicken who freaks out with terror when she sees you decides to sit on your foot to preen (honestly I held my breath so as not to disturb her).
Chickens will bring you great joy. They are quirky and chatty and all have their own personalities and likes/dis-likes (which they expect you to know and remember).
And yes, there will sometimes be tears.
All you can do is do your best and ask a lot of questions.
Enjoy the journey (and the eggs, and the poop)!
Good morning, and welcome to BYC. Some chicks simply exhibit failure to thrive. Generally it is some sort of genetic deficiency that eventually causes their death - nothing to do with husbandry.