A few simple wiring checks can be made before any voltage or resistance readings are undertaken.
There should be a motor wire connection running up the front forks pull it a part align the arrows adjacent to each other and push together up to the marked line or unitl you feel/here a faint click.
3 Phase wires can be visually checked, for this you need to access the controller wire out connections. For each wire one at a time disconnect and ensure the fitting is tight and corrosion free also check the wire end connector for a firm joint with each wire. If a sensored hub their will be a white block connector with 5 or 6 wires, check that these are firm in the holder.