The roots starved to death during the month or two after all the leaves were cut off the root-stock during high-metabolism/ active growth time of year.
Four to six good-sized leaves must be left on the root-stock until there are at least that many mature, hardened up leaves on the scion. Tender new growth is not photosynthesizing enough for its own needs, much less for the needs of the roots and trunk, which are all live cells needing glucose to survive. Remember that fertilizers are mineral supplements, not food, in the sense of source of energy to live. Fertilizers will actually make a situation like this much worse. And any disease or pest finds the plant defenseless.