My 2013 Honda Accord 4 cyl. When I started it. A flashing light appeared on the dash it looked like a AA battery. saying battery not charging see dealer immediately. This started about 4 days ago. Does not happen every time I start it. But comes on and stays on until I shut the car off. Next time I start it it my not come on. Car has 35000 miles on it. Called Honda dealer said it would have to be on before he could repair under warranty. Any advice?