Radio Staying on, and Killing battery???

95 Trans Am. I have a Pioneer Avic N2. Just recently, it seems as if the radio stays on sometimes, even with the face of the radio off. I thought that perhaps the R.A.P Module was bad, because it would make a "buzzing" noise sometimes. I changed the Rap Module, and its still occuring. Like I said, this only happens once or twice a week, but when it does, I encounter a dead battery... What could this be?

Id take it out and make sure some wires arnt touching in back, if you didnt use butt connectors or end caps and used electrical tape that might be the problem, i was going to say check to see you have it wired correctly in the first place but if you say it just started doing it, check to make sure everything is fine back there, you might be surprised at what you find