Some information that may be useful. The phone screen on my 300 failed to function suddenly after 5 years with no problem. My repair garage mechanic was unable to solve the issue. I searched the internet for a solution. Lots of traffic/videos about replacing the Hands Free Module and other cures, so I was about to source a new Hands Free Module (at great expense) and get it fitted. Then the car would not start one cold morning here in England, and a new battery was required. Battery was fitted, and phone screen fired up straight away! Totally fixed. Did it need a new battery with full power, was it solved by a 're-boot', or a combination of the two? I will never know, but if you experience the same issue, try disconnecting/replacing battery first. A lot cheaper than other possible cures.