Parasitic Battery Drain

Radio is the culprit you said ,, head unit , wiring or amp ?
Mine had an aftermarket head unit and was fine for weeks at a time. I put the original head unit in and it went flat in a few weeks, even with the solar panel on it. I just take the battery lead off when I put her away in the shed and put my solar panel on to keep the battery fresh
Also there is a difference between locked and unlocked. The battery does not drain as fast when locked. Unlocked it is waiting for something ....FUN. So they are not really asleep if unlocked