Ahh, reading slower helps. I'd still guess it's something in his soil mix or a root issue. The only thing that worked when I saw similar was cutting back to healthy leaves/wood and repotting. There are no healthy leaves left, branches are shriveling, but the trunk is still green and plump. I'd remove all the leaves as you suggest, repot, top it down to the first set of leaves and hope for the best with Spring not too far off.