Put new battery in 50 Redcat. Went to hook up wires and it was shooting some sparks. Hooked up and could smell burning with seconds. Unhooked, tried again, finally traced it down to the killswitch. There’s a little ribbed box on the frame behind RF tire. Unplugged that and short went away but now the killswitch is obviously out of commission. What is that box called? Does it need replaced or is there an issue in the key switch? I’m an electrical systems novice.

 

Little ribbed box will probably be the rectifier. You will burn it out if you fit the battery the WRONG WAY ROUND. Wouldn't have thought it would do anything to the kill switch though. Other possibility the ribbed "thing" is the CDI or a remote kill switch box.