I have got several really cheap 2.4GHz electric skateboard remote controllers from Ebay or Banggood. These controllers are great, they are cheap and they are reliable. I have been using them for over a year, didn't give me a single issue, the radio link is very stable. I also play RC cars and boats, these controllers and the receivers can be used to control rc cars and boats as well. But here's one annoying thing, the steering direction is reversed!!! And, there's no documentation anywhere to tell you how to reverse it back. I tested all of them, all of them got it reversed!!! Hunch is there's a bug in the firmware and they all had that, and since most people only uses these for skateboard which only uses throttle channel, no one finds it out! But if you are like me who have a lot of RC stuffs, you'll be the victim. Fear no more, here's a good way to reverse it, which essentially works for the majority remote controllers.
To solve this issue, swap two wires. This applies to all resistor based controls. See the following picture:
To understand why this works, let's take a look at how these controllers work. The two wires we are swapping usually connects back to the battery's positive and negative. To see how much these nob is twisted, the micro-controller measures the voltage between one of the two wires and the middle wire, as for which one it is measuring, we don't need to care. Since one thing is for certain, this is essentially dividing the voltage between two parts, if one part increase, the other will decrease with the same amount. So once wire is swapped, the voltage will be swapped as well.
I have tested this on the controllers mentioned above.