: Android 7.1 (Nougat). This typically requires a px3.img file.
Because these are aftermarket units, there is no single "official" Android website for updates. You should contact the manufacturer or check specialized forums: Phoenix Automotive Rkpx3 Android Update
: If no prompt appears, try the second USB port or navigate to Settings > System > System Upgrade Installation : The device will reboot into Recovery Mode and begin the installation. : Android 7