Ignition lock defective, contact plate?

Moin, After having for some time the phenomenon that my turn signal (mostly, but not always) continues to flash when I have pulled off the ignition key, or, I can turn on the turn signal, when the key is pulled off, I now have another ‘unusual’. A few days ago the battery was empty, car was standing on the road. Deepest charging. No idea why. Battery charged, reinstalled. Next day a neighbor came and said that on my Volvo the light is burning. It b The key was not in the ignition lock. When I had finished the car the last time, no light was burning. So the battery had been empty. In detail: If this phenomenon occurs, then I can turn on the light, turn on the flasher, and turn on the heatable rear window/mirror heating. In addition (mostly) the belt warning light starts to flash after a while, when the light is switched off. This is particularly funny, as this lamp is usually not touching (i.e. ignition) whether I’m sitting on the seat or not. This can only be prevented by putting the belt in the lock when I leave the car. What’s not possible: instrument lighting when the light is off, ventilation fan, window lifter. In short, everything that belongs to ignition level I doesn’t seem to work, and it works. Everything that belongs to Ignition Level II. As I said, when the key is removed. And not always, but mostly. If the key is in the ignition lock, then everything works. Except for the belt warning light for the driver’s seat. The phenomenon doesn’t always occur. Most of the time, however, it starts after a while after I have pulled the key. So I can go shopping for a short time, it’s all over when I leave the car, and when I come back, the full outside light and the Gur burns. twarnleuchte rattert. Can anyone make a rhyme on it? Ignition lock? Contact plate ? …???? I am grateful for every hint.