2005 sebring convertible- horn goes off by itself for 30 seconds

FIrst off the horn's ground works through the steering wheel,so the wire is bare or the end is broken and grounding in a place where it should not. You will have to check the wires for the horn from the fuse box up to the wheel.
your power feed to the headlights and the door locks has an open ( the power is not connected somewhere ) Perform a wiggle test turn on the headlights and lift the hood,find the power distribution box and begin to wiggle the wire harness.Sometimes the chrysler fuse box under the hood get loose inside the power distribution box,it will have to be broken down all the way to the heavy wires comming out of hte box,you can tighten these connections your self.