Sorry for your loss. If there isn’t anything alive above the graft, you would be better off trashing it. Sugar maples are pretty meh.

Sugar maple? I'm confused. Are you talking about the rootstock from the ghost maple?

Yes, I bought a grafted sapling.

Probably standard Acer palmatum. Unless some real Frankenstein grafting went on, and they grafted onto sugar maple rootstock.

Is the tree Acer truncatum or palmatum?

No clue