T8SG+V3 Carbon missing module CYRF6936

Hello,
My transmitter has suddenly started to display " missing modules: CYRF6936..." below which is a darkened box in which is "OK" immediately upon pressing the start button, and then, just as suddenly shuts down. There has never been anything removed from the transmitter, which worked well prior to this . Can anyone shed any light as to what is going on, and what is the resolution?
Thanks, Tim.