I went to get in my wifes maz 6 to day and the batt was dead. None of the lights or heated seats or anything was left on. I jumpstarted then car fired up and the horn started sounding, it has never had anti-theft as long as we or the previous owner has had it. She drove it around with alarm sounding til batt charged. The horn would stop sounding or go off every time we shut or opened door. Finally it stopped. She shut car off. Then got in and tried to start engine and it was dead again so obviously something is drawing power when the car is turned off. Does anyone know what could cause this??? What can I do to fix?