HELP! Revo Electric FIRE

I have a Novak 4.5 HV system in my Revo 3.3 conversion. running Reedy 2s 5000mah 7.4v (x2) to power the truck.

Truck had been sitting for a couple months and before I put it away I cleaned it with alcohol.

Got some new stuff for it for bashing, new large tires and body, so I charged up the lipos.

Ran it out a couple feet and maybe a little too fast because the tires came off all the rims in different places, even after sitting a day with a liberal amount of zap-a-gap to hold them on.

PROBLEM I ran it back to me so I could take care of my tire issue and it had white smoke coming out from under the body. I look through the window and a fire starts. I pull the body off and at the same time the capacitor hits the ground. It was zipped tied to the chassis out of harms way. It had burned through the zip tie and incinerated the 2 wires connecting it to the system into little balls of solder.

What happened?

Here's a picture of where it was mounted if it matters. Its red.