Installing the wrong firmware version can "brick" your TV. Always verify that the firmware matches your specific panel and board ID exactly before flashing.
The firmware you are looking for for the TV (board HK.T.RT2851V09 Download RT2851V09 3840x2160 Kivi 55U730GU part15 rar
To ensure you get the exact version for your device, you should follow these steps: Installing the wrong firmware version can "brick" your TV
If you have all parts of the archive, extract them using a tool like WinRAR (starting with part 1), place the firmware on a FAT32-formatted USB drive, and follow the standard Smart TV update procedure through the TV's "System Update" menu . Download RT2851V09 3840x2160 Kivi 55U730GU part15 rar
Do you have the of your TV handy to confirm if this specific file version is the one you need? Kivi 55u730gu Main Hk.t.rt2851v09 Trouleshooting - Scribd