I just bought this mazda6 from the original owner 4 days ago, when I got the car he only gave me one key for the car. And the fob wasnt working due to a dead battery. Car was running fine, replaced the battery and fob worked and car started/worked fine for next couple days. Come out this morning and the car wont turn over at all, immobilizer light flashing on the dash, battery is at 12.66volts any help would be extremely appreciated..