I would like to know if you can turn the key to the OFF position. Since you did not specify that you can remove the key, I am guessing that you can.
Just as if your key were to fail to start the car, your key lock assembly might have a broken vane or tumbler that prevent the action of turning it off.

Try this, under your dash from the steering wheel are bundles of wires. Most of the wires go to connectors. This is done so modules can be removed or replaced.
Trace from the ignition switch which bundle and or connector comes from the ingnition. turn the car on, then disconnect the connector for that bundle. If the car turns off, then you need to replace your ignition switch.

If your car does not turn off, you have just eliminated a section of the problem from scrutiny.

Good luck.

Answered by robertdebeaux
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