"File Not Supported": Ensure the file is named exactly upgrade.lgu and the drive is FAT32.
Go to Settings → System → Factory Reset . This clears any corrupted cache files from the old 9.1.3 firmware. (You will lose saved radio presets and paired phones – this is expected). upgrade medianav 9.1.3 to 1.0.13.1
Because these systems use fundamentally different operating systems and hardware (LAN5200 vs. LAN5800), you simply install the 1.0.13.1 firmware onto a 9.1.3 unit. The Quest for "Modern" Features "File Not Supported": Ensure the file is named
If you choose to keep your current hardware, ensure it is fully updated and enhanced: upgrade medianav 9.1.3 to 1.0.13.1
The units are generally "plug and play" in terms of physical fit.