How did you check the cables to motor? One single strand will give continuity. Pull on hard, if ok check for chafing by removing handle. Notorious for wires chafing under handle bottom. Contactor must be squeeky clean. Bypass the fuses to test, then can ohm out ok but carry no current. That's all it takes to to upset of of these disposable electric hand carts. People buy these for 3 grand and spend 5 fixing them!