Depending on how tiny he is, maybe he wasn't ready to be separated from parents yet. Pigeon babies are fed half digested food from the parents. Not fed like other birds, insects or worms. Baby pigeons get the partially digested food straight out of their parents beak, never saw them getting fed food "whole" like the other baby birds.
So if he is not eating food you have out in dishes, he may not know how to eat or be too young for whole food.
Pigeons are among the most successful of bird parents, baby birds are ensured of rich, easily digested food from the devoted parent birds. I think the baby birds quit getting fed once they can fly, find food to eat themselves, whether that is in a food dish or outside.
Does the baby have big bird feathering yet? Is he trying to glide or fly from higher places? Not sure if you could get a mushy mix into him with a syringe for nourishment. Maybe some canned milk watered down, bread crumbs softened, seeds from feed softened after soaking. Small, TINY helpings, fed often. Probably have some exact recipes if you do a search. Pigeons have been raised and studied for many years, so lots of information is around. Good luck with him.