Place the extracted firmware file (usually named allupgrade_ms338_sos.bin or similar) onto the USB root.
When a firmware file is uploaded in parts (Part 1, Part 2, etc.), you have all parts in the same folder to extract them. Download both Part 1 and Part 2 .
Press and hold the Power Button on the TV panel (not the remote) and plug the power cord in.
Right-click Part 1 and select "Extract Here" (using WinRAR or 7-Zip).
What is the with your TV? (Boot loop, no power, etc.) Do you have Part 1 already? What is the Panel Number listed on the internal sticker?