Just a thought...There is a lithium battery in the M8 that retains all the settings....when that battery goes bad, it loses ALL the display functions....acts as if theres no power to the radio. You get no display at all. For what its worth.....the batterys only last a couple of years, but they are replacable. I live close to Airtronics and have them replace it every year or so (my radio gets LOTS of use). Good luck, and let us know what it turns out to be.