What he needs is a good set of friends. Not just acquaintances who he sees during an event (like say volleyball) and never again, but a couple friends(or atleast one) who with whom he feels like he can hangout with all day, year round. That'll help greatly with the depression. Even if they stare at a screen, they'll do it together. I speak from experience.

Now how you can help him get a couple good friends, I don't know. It is something that has to happen very organically. Forcing it won't help in most cases (you'll know within a couple interactions). Don't try to push him to events he doesn't want to do. You can be around hundreds of people and still be lonely.