Vehicle: 2000 Dodge Durango V8 5.9L 4WD 220,XXX miles, well maintained

Symptom: Engine remains running after ignition switch is put in the "off" position and key is removed. Dashboard lights and gauges are on even with the ignition in the off position and key removed. Engine starts and runs just fine with normal operation of the key and ignition.

Engine, ignition, and starter were all working fine prior to this. No abnormal engine sounds / smells.

Probable contributing factor: The upper radiator cap and tee fitting cracked and hot coolant was sprayed in the engine compartment. Engine was shut off before engine reached overheated temperature (this is the last time the ignition switch successfully turned the engine off), there appears to be no other damage or issues caused. The next day I noticed the dashboard was on without the key present, started the engine and it wouldn't turn off with the key.

 

Sounds like the actual ignition switch in the steering column went bad to me.

 

Gremlins. Yup.
Sounds like something got wet and shorted. Once things dry it may work again. If it does, antifreeze seems to take forever to dry, wash under your hood with a pressure washer and see if it happens again.