I'm so sorry for your loss, don't be too upset; you gave him the best life he could have until he passed- at least his last moments were with people who would do anything to help him.
Oh no!!! I don't really know how to help, maybe his crop and the bottom of his beak is filling up??? Avoid feeding him too much liquid, instead try to drop small bits of bread crumb or chick crumb into Maverick's beak.
Give him a chance!!! I had a weak chick (too weak to even hatch), we thought he wouldn't make it but now he is 3 weeks old and strong as ever! Just a litte smaller than his siblings!