How can I keep a baby wild bird alive? What kind of food?

Found baby bird, barely 1/2 oz, no feathers and eyes still shut. No sign of parents and no nests in the area. VERY hungry, I'm feeding him from a syringe with pureed meat and Enfelac, also hardboiled egg yolk mixed with sterile water. Have him on a heating pad (low) in a plastic bug-box with airholes. I know his chances are slim, but any input appreciated! We have named him "Peep" - he is very vocal and responds to my voice.