Different firmware versions may map the buttons differently. Why "Part 20"?
Plug the USB drive into the (usually the white or black one, not the blue 3.0 port). Download CV960XH A50 3840x2160 Magic55 Update part20 rar
If your TV brand is listed (e.g., Skyworth, Hisense, or local rebrands), check their official "Support" or "Drivers" page first. Installation Checklist (Don't Skip!) Different firmware versions may map the buttons differently