I jus gotten a head unit install in my car not too long ago and on my way home all of my car meters dropped to zero and the car started to jump as if it was running out of gas. roadside assistance put a charge on the battery but when you put the car in drive it shuts off and is dead again. when i got it to my insurance company they said the security system chord was loose or off . what does that mean? does it mean i may need a new battery or alternator or what is it in general? PLZ help