2018 BRZ -- Head unit won't turn on after iOS 13.0 Carplay. How to reset?

[hushypushy]

I have a 2018 BRZ. Last Thursday (9/19) I downloaded the new iOS 13.0 to my iPhone 7 Plus. On the way home from work, the new CarPlay was great!

I parked the car, turned it off, and a few minutes later I went to visit my mom, and...the entire head unit was completely unresponsive; it wouldn't turn on. It would light up with the interior lights, but that's it.

When I drove home, the head unit turned back on. So I assumed it had just rebooted itself. And of course I just plugged my phone back in and used CarPlay again.

Next day, I drove to work and the head unit would not turn on. Since then, I've driven the car several times and it still won't turn on.

When the lights are on, the unit seems to reset every minute or so--the lights briefly turn off and then back on again. Also, if I connect my phone to USB it sporadically disconnects and reconnects. So it seems like it's constantly rebooting.

I've disconnected the battery twice, once for 30 seconds and the other time for about an hour. The cluster settings (rev light, etc) were reset, but the head unit still remains blank.

Any suggestions?


(and yes, I know it's under warranty, but if I can reset something myself in a few minutes that would save everyone a lot of time)