Accept Screen not responding

[14thbmw]

Hi gang,

Nav screen has the Warning with “Accept” by the lower right button when the beast is started. Recently it has intermittently not responded to the button push, meaning the screen stays in the Warning mode and the radio, etc cannot be used. B/C still scrolls through the items on the dash display.

Sometimes if I turn the beast off and remove the key for a few minutes it will start working, but it increasingly is not responding even to that.

Garaged, about 170k miles, ambient temps in low 40s F lately but warmer in the garage. All other electronics working fine including seat heaters (which usually seem to be first to go when there is a battery/alternator problem). I put it on a tender to top it off anyway.

Any ideas what could be wrong or what to do to get it responding?