2002 Ford Taurus Won't Start

When I jump the car, it'll work for a a few hours and then the next day, I
have to do it again. I went to a mechanic, we tested things and the alternator
is fine, the battery works but I believed something is draining the battery. As
told, I changed the GEM module to an new one. All the lights turn off and
nothing is connected to the car charger ports. I do have a third party radio,
but that turns off as well when I'm done using the car.I jumped the car
yesterday and after I turned it off, I disconnected the battery (hoping the
battery doesn't drain) however, the car still refused to start.