I know this thing. Happened to me twice but worked properly after restart like you said.
There's kind of error in the device software. If you turn the key without starting the engine all electronics including the radio is on. In this state you can switch off the radio manually by pushing the ON/OFF button. If you then start the motor the radio won't play doesn't matter what buttons you try to push, it will only show *CHRYSLER* on the display. You have to shut off and restart the engine (I hope you understand my explanation).

The problem rajunz described seems to be something else ... sorry, no idea.