Key won't come out of ignition

Could be an ignition switch going out or wiring issues. I recommend finding a good independent shop and get then to check it out. If you keep disconnecting main power your going to damage the computers.

The ignition switch holds the key until the engine is turned off. You have a defect in the switch, and it needs to be replaced. That's pretty involved as you'll have to get a different key and reprogram the car to the new switch and key. Best left to an automotive professional to do.