87 Mustang GT starter problem

So I was drivin down to Quik Trip to grab some gas, and I noticed the radio went out and came back on prior to pulling up to the pump. Didnt think anything of it until I went to start it after getting gas, nothing happened and soon after nothing happened smoke starting coming from my hood. Opened it to see the negative battery cable completely melted from the wires and was welded to the battery. Replaced the terminal and tried again a few days later, then the positive cable caught fire and melted haha. Im at a loss, other than thinking that maybe I wired the starter solenoid wrong when I replaced it. (I put the wires back on exactly how they came off). Im at a loss, please help me get my Mustang runnin again:runaround: