In reply to Nhex.

One more thought about this -- I'd gotten so used to "upstairs" meaning either "heaven" or "the boss" that it didn't even occur to me that for the pople in the complex, "upstairs" means the kids and "downstairs" are the ancient ones. So basically, I think you're exactly right: it's not referring to divine intervention, but the fact that somebody upstairs (Marty) messed with the electrical system enough to ruin the cave-in.