Visit the official Dynabook (Toshiba Support) Portal and enter your specific model number (65U7750) to see if a downloadable USB update is available.
You must have every part (Part 1, Part 2, etc.) in the same folder to extract the firmware successfully. Download TOSHIBA 65U7750 Panel K650WD7 LF330 part3 rar
Open Part 1 with a tool like WinRAR or 7-Zip, and it will automatically combine the remaining parts. Visit the official Dynabook (Toshiba Support) Portal and
Select or Update Now to download and install the latest version directly over Wi-Fi. Via USB (Official Support): Download TOSHIBA 65U7750 Panel K650WD7 LF330 part3 rar