The software will automatically pull data from Part 2 and Part 3 to create a single usable file (usually ending in .bin or .pkg ).
Plug the TV back in. Some models will detect the file and start flashing automatically.
Multi-part RAR files are a single archive split into smaller pieces. You cannot use "Part 3" by itself; you must have in the same folder.
Firmware updates are risky. Ensure the firmware version matches your TV's mainboard model exactly to avoid "bricking" the device.