2002 Buick LaSabre Electrical Issues

Buick sat for about an hour yesterday evening. When I went to start it again, the battery was dead. All the dash lights, dome lights, ignition “ding” and parking lights remain on - even when I take the keys out of the ignition and close the doors. I disconnected the hot wire and waited 15 minutes or so to reset the computer. Reconnected it, then called for a jump.
Got a jump from a friend, and after charging for about 40 minutes the car finally started up again and I drove it home.
Then when I shut off the car, everything (lights, etc) still stayed on as though the keys were still in. For the night I disconnected the battery, but what do you think could be causing this? Computer issues? Security system? My battery is still in decent condition. I’m so lost right now.

(A note: Before this happened, my door locks would all randomly lock while driving down the road, but this has always happened for the year I’ve owned the vehicle. Assuming there’s more wonky electrical stuff going on)

This would be normal if you had a poor connection at the battery or a ground cable from the chassis to the engine or battery.

As far as everything staying on with the key out of the ignition that is a tough one.
I did have a car brought to me that had this problem. It came in late at night and I just pulled the positive battery cable to keep it from discharging the battery over night. By the time morning came, I hooked the battery back up, but could never get the problem to raise it’s ugly head again. The owner was my brother and he never had it happen again in the next three years he owned it. Sorry!!! Evil spirits!!!

Yosemite

Could be a faulty ignition switch or body control module.

I assume all the things you mentioned that are ON, including the dash lights, normally turn on when you open the door. If that is correct then I would suspect the door latch switch connection isn’t opening when the door is closed.

Good ideas above. My guess is the ignition switch is faulty. btw, for safety-sake, when you disconnect the battery, it’s best to disconnect the negative terminal, not the positive. It’s very easy to get a short circuit if the wrench touches most anything metal in that area. You definitely don’t want to be holding a wrench with 800 amps going through it.