SDL
I have the same problems but I have noticed the system seems to be more stable (less crashes) if I don't plug anything in the USB port. I had an iPod plugged in and noticed the system crashed more often. Just using bluetooth connected iPhone for telephone and music streaming right now. Do you use the USB for anything in your car?
Unfortunately, the reason why I began using the USB is because how unstable it was while connecting to my phone. I figured by not using the phone's Bluetooth audio, it would be better. And it was for a few weeks, then the crashes returned. I honestly think it's something to do with the Bluetooth connection. It all started when I first paired my Bluetooth (which I have unpaired and paired again since then). Even while I was on the phone with customer service from Mazda, my phone was losing connection. It would disconnect and connect. I disabled contact syncing this morning b/c sometimes that gets hung up.
Something in the process when you first turn the car on and the phone is syncing causes the screen to go blank. You can still keep talking/listening to music, the infotainment system works, but the screen won't come back to life. Today, it happened as I started driving, so I had to wait 15 minutes until I got a red light to turn the car off/on. Hard reboot did not work.
Note: Using a Nexus 6P.