I found a baby bird, How can I tell if it is alive?

I'm 98 percent sure he is dead, but it is so sad! Is there a way it may be in shock? How do you tell? I tried to warm it up on a heating pad with a blanket. Its eyes haven't opened yet and only has a few tufts of grey fur. I found it on the wharf, there are no trees around, so I think something must have carried him away and dropped him. Why would they leave it? The bird is not stiff, so it couldn't have been dead long. Can you see things breathing if they are in a hypothermic state?