Radio coming on when car is off and locked

[Clawliger]

As the title says, I occasionally come out to my car after it's been off and locked for a few hours or over night. And the radio is on and playing. If I leave it on aux setting when I turn the car off and I discover it's on, it goes to the radio everytime.

Earlier today I came out to the car and the battery was flat. Nightmare.

I've searched for ghosts but no luck. Help!

 

[Clawliger]

Bit the bullet and replaced the battery as I'm pretty sure it's the original item. Hope it fixes it.

On a side note, when I pulled the fuse under the steering wheel labeled radio. I could still turn the radio on and off but I only lost a/c and rear heated screen functions. Is that normal or?