Move it to shade but that's it. It must stay outdoors. You removed 50% of the root but you left all the foliage (or at least that's what I gather from the thread). That threw the tree out of balance, so it has to regrow roots to re-balance itself. No surprise foliage died, not enough root to support it. So you have to nurse it back to health, but nursing is mostly leaving it alone. The leaves that the tree can't support will fall off on their own. Once new root growth begins, that will be followed by new foliar growth. Outdoors in shade, don't water until the top of the soil is dry, that's it.
In your experience, do rooting hormones do any good? Or will it recover all on his own? Sorry I ask so many questions, I’m really worried.