So sorry to hear it. Sometimes it's hard when they make it and you have a scrawny, weak chick who needs special care. Sometimes they do great so it makes it worth a try. It's always hard when you lose one. Hope the rest of your hatch went well.
Wrap its body in plastic, the biggest danger is the yolk will dry up before it absorbs. Maybe zip lock bag with its head out and wet paper towel wrapping it up. Put it back in the bator.