Have ya tried any warm, mushy comfort foods? have you tried feeding him off your fingers?
He come home with you yesterday, right? Seriously, I wouldn't get too worried yet. He may be eating and drinking some when you're not noticing. Has he had any poops? If so, are they normal birdie poops? (sorry to be gross, but if he's having normal poops it's the best indication that he's eating/drinking.) Put fresh papers under his cage and then check the papers in a few hours and see if there are any poops. Ahhh, the fun life of a bird mom - poop patrol!!