What should I check first? All the gauge aren't working except for my engine temp, that's the only one that does work. My mileage is frozen my speedometer is on zero as well as my tach. My gas is stuck on 3/4 of a tank. My oil is all the way up my battery is all the way down. They were working fine then all the sudden I went out to my car, turned it on to find this. It's been about a week. Any help???