I need help with my bird! I don't know what's wrong! URGENT!?

I have a macaw, he's about 5 years old and i left him with a friend for a few days. I just got back and his food and water were gone, but i had only been gone 2 days so i thought that he would be okay if i just fed him again. I woke up this morning and found him sitting in the corner of his cage, not touching the food and not moving at all! It had been a bit chilly at night but nothing under 60. I honestly thought that he was dead and after about twenty minutes removed him from the cage. He was still breathing! I moved him somewhere warmer, and have been watching over him for the last hour or so with no change! He had come from an abused home so he wasn't very friendly at all, I couldn't even get near his cage without him lunging to bite me. Now I can pick him up and he won't even move except for the occasional leg kicking at my hand. It's like he's hibernating, but birds don't do that--do they? Please help any comments will be appreciated. Again, he's still breathing so i know he's not dead.