Pressed the Start buttun and entire car electrical goes dead

Matty13

I bought the car last week and just joined the forum so forgive me if this has been covered.

Left work tonight and the car started fine. I stopped on the way home at a gas station. When I went to restart the car everything appeared normal. When I pressed the Start buttun all of the electrical went dead. I got a jump and the car started fine. Drove home and everything appeared fine. Turned the car off and everything was still working properly eg. radio, headlights, dome lights, gauges. Tried the Start buttun again and again everything goes dead. All of the electrical and the car won't start.

I saw the key fob thread but I'm not sure this is the same thing. Based on what I know about the car the battery is fine. Any ideas. It's and '09 base 370z.

Thanks guys.