Will not stay running?

I replaced the starter alternator and battery, and I was driving it fine then while driving it shut off in the middle of the road. So, then I got it home by towing it. And found the starter positive wire was touching the catalytic coveter and melted it a little. So, I covered the wires and made sure they weren’t touching, and it still needed a jump start and when I take the jump starter off it shuts off.

And then there is a wire the it has a plug that plugs into the whirring under the battery, and it is a thin wire that is cut and has voltage that has been like that since I got it.
Pearl