Use a magnifying glass to look inside the Revo Mainport for bent pins. I bet that is the problem, and the Mainport does not work at all. A bent over pin can be straighted with an #11 Xacto to move it a little to start with, then very very very thin needlenose pliers or hemostat to clamp over the pin to straighten it.
Also, I fixed a clone Revo for a friend that had a tiny solder short on Mainport. The tiny chip with the protection components close to the connector.