You must download all parts (Part 01, Part 02, and Part 03) to the same folder on your computer.
Open only Part 01 with a tool like WinRAR or 7-Zip ; it will automatically pull data from Part 03 to rebuild the full firmware file. Download MT5522S PC822 3840x2160 AKTV4636S part03 rar
Release the button when the standby light starts flashing (indicating the update has started). You must download all parts (Part 01, Part