Overnight battery drain

You will have to disconnect the negative battery cable at the battery and then place an DC ammeter inline with the disconnected cable with the negative lead on the negative battery post and positive lead on the end of the cable. The DC amperage reading with everything off, key removed should not be more than 50 mA, that is 0.050 amps. If it is and I suspect it will be, start removing the fuses one at a time until the ammeter drops safely below 50 mA. Then find out what on that fuse's circuit is causing the problem and start by first hooking the battery back up, put all the fuses back in, power up that fuses's circuit and find out what does not work on that circuit. it may give you a clue as to what is causing it.