There is no power to car. I put in a new batterery. The horns works but nothing else. No lights on dashbord.

If the fuse blew, most likely the new one you installed also blew. Check it again. You have a short somewhere. Double check all the wires you did while installing the horn button.

Sounds like bad horn. Run Power from battery to horn and see if it works. If it does problem is in the wires going to it. If not replace horn

It sounds like you have a problem with the starter solenoid or the starter relay. Usually, a "click" heard under the hood with a good battery indicates a faulty starter solenoid. In this case, the starter wants to work, but the solenoid which is usually attached to it won't transmit the necessary power to run the starter and crank the engine. Starter replacement is the only remedy in this case. If the click is heard from the fuse box, then it may only be a relay that is the culprit. Try swapping the starter relay with the horn relay or another one that has the same part number. Be sure to also check that the battery connections and grounds are clean and tight.

You need a wiring diagram to start your testing

Guessing won't get it,waste of time

It is old enough to be a fusible link corroded

Some things work some don't,starting circuit
included if not a bad starter & separate problem

You can solve almost looking at a wiring diagram
as you know what deosn't work

I too am having horn problems with my 2005 grand am . Although mine died slowly I rode the horn infront of a friends house and I could hear it changing pitch dieing out so to say. Soon after 2-3 weeks I would check to see if it still messed up then nothing. Ive gone through every fuse and tested all the power up to the actual horn under the hood because Its hard to hold a test light under the hood and press the horn but I put my top dollar on its a defective horn. They kept alot of defects on the hush hush , Turn signal relays going crazy , timing chain noise , Defective tire bolts poor thread, poor transmissions , power seats , Nothing that causes wrecks so no mandates yet. The + to the whole story is GM did make this car stupid easy to work on and parts are at a fair price. They are dime a dozen in a junk yard you can swap alot of parts from the cavilier , alearo , sunfire , HHR , Ps dirty oil kills this motor faster than anything the new tech in this stuff count alot on never gumming up and keeping a clean everything.Its not like the older cars 1970 where things clear them selfs and building a strong motor was the only factor.Good luck with the horn It also has a relay in the fuse box under the hood bottom left if your standing infront of the car. I belive you can grab the one right next to it the one for the fog lights and swap them to test it out they are the same.By the way all in all I like this car.

Maybe horn became unplugged. Put 12 v power to horn make sure horn works. Put test light on terminal on horn have someone press the horn button, if light comes on and horn does not blow you may need new horn. if light does not come on you may have bad contact at horn button, blown fuse, broken wire, bad horn relay or possibly just a bad ground.

You need to start with checking the fuses, sounds like they are blown. Fuse panel is on side of drivers dash, you need to remove panel, just pulls off.

Troubleshoot the starter. If your battery is good, then you WILL have power...the lights will work, horn, etc, but....if the starter is toast...you need a starter.