I had usb issue in 9th gen as well, but it wasnt stuck or volume issue, the problem was that there were 2 songs being played from the usb at once and i could control only 1 of them. If i paused the music player only 1 song would pause, the other would keep playing. I tried to find a way to hard reset in settings but there was no option and there is no power button like a normal android phone or tablet. I tried pulling the usb out but it kept searching for songs and the moment i plugged the usb back in, it would start playing that song in the background so the only way to fix it was turn off the car for a few minutes which is very annoying on motorway if u have to stop the car just to fix the music player.
After this happened a few times i just started using bluetooth and play songs on my phone
