Electrical problem
1999 GMC Savana V8 Two Wheel Drive Automatic 171000 miles

My vehicle won't start when I turn the ignition. No power is applied to the dash, no headlights work either even when the ignition is off. The only thing that works is the battery-reset switch, which only triggers when the battery voltage drops lower than nonimal. However, normally when I hit the reset switch, the car alarm goes off. It doesn't when I hit the switch.