Select or Update Now to download and install the latest version directly over Wi-Fi. Via USB (Official Support):
Navigate to > Support (or Device Preferences/About ) > Software Update .
Visit the official Dynabook (Toshiba Support) Portal and enter your specific model number (65U7750) to see if a downloadable USB update is available.
Multi-part .rar files (like "part3.rar") are common on community repair forums because firmware files can be too large for single-file uploads. If you have already found a specific blog or forum thread: