2004 Oldsmobile Alero 2004 Alero kills batteries dead over

My daughters car has gone through two new batteries in 10 mos and recently intermittently kills the battery (fully charged) dead over 2 nights. It can run 50 miles and park then be completely dead, has a new alternator, new battery (tried 3 different ones) and have visually checked all cables and even frame ground. Something is drawing down the battery overnight. I am told that the vehicle module is 20 minutes and should not "awake" but something draws this down after two days of idle use. The cables to the battery has been double checked, but I noticed that the remote door lock on the key no longer works but the door switch is working. It does have a after market radio that I purchased in the car from the dealer and the new alternator is showing on 45 amps at times while running, but mostly runs at 60 amp. Any suggestions are appreciated.