Covid hasn't made this easy on many people, because so many of the standard responses just aren't possible right now. Lots of people think you just can't help but feel the spirit when on BYU campus, but that's not true for everyone. Sometimes depression just doesn't let you feel much of anything, good or bad. I'd start with making sure he's eating well and getting some exercise and sunlight, then move to zoom therapy or meds if needed. That may be enough of a little kicker to give him the energy for school, making the effort to forge friendships, and get into the weeds of how he feels about the church/gospel