Simple really, its like a light bulb and two wires once the battery has a postive and negative it creates the open circuit.
You take away one side it would be called a switch or closed circuit. You need to see if the horn is somewhere stuck open i.e the connection at the horm itself or the pusher is stuck connected. Reading your posts the push switch makes no difference so I would just either replace the horn itself or test it out if you can make it honk by by passing a seperate positive and negative battery feed to test it! Hope that made sense? There can only be three things wrong horn, wires touching, push button touching. Thats all there is to it really. Open or closed noise or no noise.
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