So two weeks ago I had a 11.2 inch DVD player roof mounted by a audio shop. Looked good, everything worked fine. few days later had a dead battery. charged it and worked good for a couple days. died again. so got a new battery thinking the old batterys time had come. new battery lasted two days then that was dead as well. Called the audio shop and they said it couldn't be their doing, as it was only an accessory line, powers down by itself etc. If it isn't the install of the new DVD player, what is the problem?