I would recheck all the things you have listed.. i feel that if they are safe, warm and full they will not cheep..
When I was newer at this, I had that problem often.. would curse at them and threaten to throw them out the window or fireplace it was me// if t hey can get away from the heat they will so ... but if they are huddled up under it and still cheeping id put a higher wattage bulb in the lamp so they would not want so close to it.. and try that..
and water sometimes they dont know how to do it..they have to be trained how to find th e water.. i always dip their noses in it several times a day when t hey are young. at least the first day..and make it visible i put red marbles in it to get their attention.
and i fill their bellies up (or whatever) with a batch of Ramen Noodles. they love this.. love it and it is so much fu n to watch.. i cut them up in tiny peices and they go to town.. this is my way of teaching them to eat sooner. t hey will attack that stuff like candy.
ive been doing that for years and have not to my knowledge lost a single chick from it.. and too my chicks grow much faster than the momma chicks..
last hatch i had eggs under a momma that had 4 days to go after the first ones and i had to take the eggs out and hatch them in my incubator momma had four and i had four and mine were 4 days younger than the first ones.. mine were much larger and smarter than hers.. yep..hahah when their bellies are full they go to sleep... solid
the only difference was the ramen noodles now i make sure my babies get the nooodles soon after hatch..