98 Monte Carlo z34 will not start

Please help my 98 started acting up a few days ago. When you turn the key to run it would trip out the dash (gauges going everywhich way and looks like christmas) but if you turn the headlight switch on it would go to normal and I could start it. Today that didn't work turn key to run and same thing no power anywhere starter won't crank. Plus if you turn headlight switch on, no lights and nothing else works either. Sounds like a short in headlight circuit any ideas where or other input?

thanks