Firmware upgrading is done via placing the upgrade_loader.pkg file on a USB flash drive, insert it into the TV, press the OK button on the remote & switch on power.

The firmware files are some kind of encrypted, a string command on this file gives us just a few boot messages.

I am not sure what exactly is overwritten with the firmware upgrade, because even with a firmware from a different TV manufacturer, I still got the Medion logo on startup.

You will find some different upgrade files, but be warned: this PCB works with different screens, so some funny things might happen (picture upside down, bricked PCB,...)!