Well....I put my LGB G scale Amtrak on the track and it did the same thing. I think I overpowered it as I run higher voltage to the rails then it runs on. The other matching car just lost it's lights. So I rebuilt the electronics boards inside both and added LEDs.
I don't see what burned out. I do know that it must have been something to cause an amp draw go so high.
Maybe something in your circuit went out? Is this car lighted? does it have a switch underneath to shut off the lights? If the short goes away with the switch off then something will be easier to locate.