Starter tried to start w/ key off and out of ignition. Starter burnt up. Replaced starter, Before connecting starter wires checked voltage. Starter wire 12v when key in start position. starter wire 12v when key turned off???
Sounds like some wiring harness damage may be the cause. But most common cause would be a sticking Starter Relay.
Starter Wiring Diagram 2004 KIA Sorento