2002 Cadillac DeVille - Dead electronics

, no interior lite, gas lid, truck lid buttons do not work ,windows head lites, do not work, car would not turn on unless use battery charger

Sound like a dead battery, have you done any checks on it??? Could also be loose and or corroded battery cable and or ends… Could be lot of things…

First step, ask your shop for the standard battery/charging system test.