I heard a salesman did this one time. Go into the calibration mode and calibrate the travel pot. It is possible you have cables switched to the drive motor, but I think the contoller will sense this and lock the brakes.

To calibrate, you just get to the travel pot calibrations and hit the enter button (also called the return key of the 90 degree bent arrow button. You push the handle forward, hit enter, push it to the center and hit enter, then reverse and hit enter. You will then have to get to a place where you escape back to the main menu and it will ask if you want to save the new settings. You want to scroll up to where it says yes and hit enter and that should do it. If you have the standard disply where it is just giving numbers instead of actual words that tell you where you are in the menu, I will have to go into more detail or you need a book. Also, the diagnostics on this truck will allow you to look at all the switches. This will tell you whether the forward and reverse switches are closing and opening properly when you push the handle forward and reverse. This is the " analyzer" mode.