Download all parts (Part 1, Part 2, etc.) and extract them using WinRAR or 7-Zip. You must have all parts in the same folder for the extraction to work.
Insert the USB into the TV's port while it is off. Turn the power on; the standby light should blink rapidly, indicating the update is in progress. Download MS358 PB801 1366x768 512M USB part3 rar
Firmware for these generic boards is often hosted on technician forums and YouTube tutorial descriptions. You can find related software and installation guides at the following locations: Download all parts (Part 1, Part 2, etc