Cedric might have to physically restrain Howard at this point. Howard keeps slamming up against the top of the coffin, although they're pressed so tight that he can't get his knees under him so he's mostly just whamming his head and shoulder into it.

"Oh God, oh God, help, we're still alive!" He starts scratching at the walls, although deep down he knows that won't help either. And that's the worst part. It's just waiting for rescue, rather than being able to do anything, and he can't stop freaking out.