How do you keep a stranded baby bird alive?

A bird made a nest in our garage. Since I noticed the bird in there I have been leaving the back garage door open so it could come in and out. Today I walked in the garage and saw a baby bird laying dead on the floor. I decided to get a chair to see if there were any more babies in the nest (I had never gotten anywhere near the nest prior to this because I no birds will abandon them if you do). There wasn't a bird in the nest but the last one had crawled out of it's nest and was about to fall to it's death like it's sibling so I decided to bring it inside. My kids went down to the store and got some night crawlers (worms). We cut four small pieces off of one of the worms and the little bird gobbled them right up. What about water? Do baby birds drink water or do they get that from the worms? Am I waisting my time trying to save the bird? I took the birds nest and placed it in a box and that is where the little bird is right now. That will have to work until I can figure out something else. Any ideas? How do I keep it alive until it is old enough to go free. Right now it can hardly move around or open it's eyes. No feathers either!