I have a older one of this creatures at work and last night before work was over I finished putting a new plug end that connects to the battery that is similar too the jumper cable sets. Well after I got the new end on and plugged it in the thing will not go forward or in reverse but it will go up and down and the horn works. The bare wires did accidental touched each other but for a brief second and arched. What could I have screwed up? and how can i fix it.

 

Take the rear panel off, and have a look in there, disconnect the battery pack first though. There are fuses in there, among many other things. It is quite possible that the quick zap may have taken out a fuse for the travel. Or possibly stuck a couple contacts together in the safety system.

Once you get the panel off, they are pretty simple machines to deal with.