Thanks for the super detailed description, you've saved me literally thousands. In Canada, these taillight assemblies are 1600+ and another 800 for the sensor. That's what the dealer quoted me - and recommended replacing everything.
My lens was also full of water (about a cup). I read your...
Thinkinking it over, in my case I think it updated from 3.3 to 3.4 in my driveway. Then it went black while driving, and I needed to stop and do the reset to finish the update
I had this problem today. The screen just went black. But the backup camera was working. So I did a soft reset - volume plus fast forward for several seconds, then sync rebooted and the screen came back up with a brand new UI. Seems like I received an update. Kind of awkward to have to do it...