Approach Z82 - Not able to exit diagnostic mode ?

My device has for unknown reason entered diagnostic mode, and now I am unable to exit back to normal mode following available procedures ? - The light turns purple, but never changes to red - Seems like "up" bottom not working ??

Device is updated with Garmin Express to latest 4.4 software version, and has worked perfectly for nearly two years.

Any suggestions to get back to normal mode, thanks ?