I just got this car used a few days ago and noticed that about half the time I got to turn off the engine, the radio/screen stays on. The other half everything powers down as it should.

Why is it going to accessory mode instead of just turning off? It seems really random and I don't want my battery drained from this.

 

Sounds like an ignition issue. Sometimes the ignition isn't turning your car off. Have your local Honda Dealer have a look.

 

I think if it is on ACC it is supposed to do that..... until you turn the key back....