Unfortunately the chick has just died, but thank you for your support and suggestions.
The broody has been taking very good care of the chicks and the others all seem very strong and energetic.
Chick is about a week old and belongs to another family member, said family member found chick early this morning lethargic and lying flat on its chest, brought it inside and put it in a basket with a hot water bottle and gave to me to take care of. Both the chick and the hen that's brooding it...