Q: Car won't turn off

I had my Tahoe washed yesterday and I drove it home right afterwards. I turned it off and took the keys out and the engine was still running, not the fan, the engine. It was running just like it does when the keys are actually in the ignition and it's in the "ON" position. Everything in the interior was off and it wouldn't go into gear but the engine was still on. I disconnected the battery and it still ran. The only way I could shut it off was by pulling the fuel pump fuse. We replaced the ignition switch and it's still doing the same thing. Now today the battery is completely dead. Tried to jump start it and the interior lights turn on and the motor tried to turn over 3x but then it stopped trying to start. The temperature on the rear view mirror stays on and a check engine light stays on until the battery completely dies again.

My car has 120000 miles.
My car has an automatic transmission.