Mercury died
 

While driving my engine just died. I still had lights and dash lights. Engine would not restart. I coasted to a safe spot. The headlights shut off, then all dash lights and security light came on. Engine would not start. No starter sound. The security system would not allow me to restart. Dash lights flashing. About one month prior, a similar incident occurred after I parked and came back to restart. A website I found suggested I turn the key to on and wait ten minutes, then turn off the key and wait 20 seconds, then try to start. If nothing happened to repeat the procedure three times. After the third attempt all dash lights went out and the engine started. All was good until now.

I would start by removing and cleaning of the battery connections and all grounds. There are many grounds located on the engine block, fenders and inside behind kick panels. "Looks" ok isn't good enough. Remove and clean is what should be done first.