Mine completely froze too... the stereo was on, I couldn't change the station or turn the volume up or down, it felt like the car was possessed. The folks at SYNC walked me through doing a 'soft master reset' which didn't help, and my dealer told me to come in the following day for a hard reset. After some research, I discovered the fuse 67 thing above and it worked instantly and like a charm. On the 2013 C-max it is in the passenger foot well, remove the panel (look up, you'll see it there, where the ambient lighting is). Now I couldn't actually find fuse 67, but there are these large fuse panels, I opened the 2nd one from the left, my screens went blank. I closed the panel and sync rebooted instantly.