Since I upgraded to iPhone 6 last year, my Entune audio really never worked with "iPod" source. It would get stuck on loading screen most of the time. Yesterday, I decided to take the car (2012 Prius III) to dealership to see if they have an update for Entune and apparently my Entune system was way behind, so they decided to upgrade it to the latest version, BUT half way through the update the install process froze and they couldn't quite finish it. The result is that my car is now stuck in "System Update" mode and I can't use anything in infortainment system except FM radio and CD. They called Entune support, but couldn't figure out a solution. Ultimately, they ordered me a new "Radio"; I am not sure what this means, but I will go back there next week to get my system fixed. I found some entune upgrade link on this site and I was going to just download and try it myself. I work in IT and I thought how hard could it be. I am so glad I didn't. Luckily, the car is still under warranty and I didn't break the system, so it is between dealer and Toyota at this point. TLDR: Entune update bricked my system. If you are having problems with your entune system, take it to your dealership. Don't try to upgrade it yourself.
