94 S500 Has Power Won't Turn or Start
 

Today, all of a sudden, when I turn the key to the start position nothing happens. This has never happened before!
Two weeks ago Benz dealer reset codes and advised that a safety switch may have caused the engine light to come on. He advised me to drive it and return to him if the light comes back on. It came back on.
Sometimes when the key is in the off position, the warning buzzer sounds when the door is opened as if the key is on. Please help!