i had two light brahma chicks hatch in an incubator and after 5 month put them in the coop. they were fine for 2-3 weeks. then there was a 10 degree drop(below what it was) in the temperature one night. one chick died. then it was about that temp. for a acouple weeks. about 3 days after the first chickk died the second one died.they didn't freeze because the went frozen like ice cubes even though the air temp was 60'ish. they were slitt flimsey like the rigimortous had not set in. what happened?