Mechanic Job in Chesapeake, Virginia

I have a 2005 Cadillac STS. I had it sitting for two years and am trying to get it up and running. I had the battery replaced and it ran well for two days then the car completely died. Eventually the car died while driving it In my neighborhood. There was no power and it definitely isn't the battery. I had a tow truck come and they gave me a charge and I was able to make back to the house. After returning , the car wouldn't start again. I need a complete diagnostic to see how I can get my pearl running again.