On Friday night my Model 3 LR RWD (December 2017 build) screen went dark and unresponsive. This happened while it was sitting parked. Although I was able to do various things (turn on the headlights, move the seats, etc.) the display was quite dead. Scroll wheel reboot did nothing. After getting no useful help from roadside assistance I decided to let it sit until the next day to see if it might behave better. Since roadside assistance offered only to have it towed I didn't bother with them again. When the screen remained unresponsive the next day I drove it to a service center. This was no doubt not legal, since I had no speedometer or turn signals, and probably no brake lights. At the SC they tried to do a quick hard reboot. No luck, so they told me they would have to keep it and they'd get to it in a few days since they were busy. I got a loaner, so that was fine. They diagnosed it on Monday and replaced the MCU. I got it back Tuesday. My car lost (almost) all state. No name, no user profiles, no navigation favorites, no home address, no trip info, etc. The only things it seemed to have retained are the odometer reading and its key info (both phone and card). Can anybody confirm for me that this is expected behavior? One other disturbing thing is that I had 2019.36.2.3 when I went in, and 2019.36.2.1 when I got the car back. I didn't think going backward was even possible. Anybody know if this could cause any problems?