Try a smaller USB drive (8GB or less) or a different USB port.
How to Find and Install HV553 3840x2160 MAGIC 65JP65UASG Firmware Download HV553 3840x2160 MAGIC 65JP65UASG part02 rar
This software is specifically for 3840x2160 (4K) resolution. Try a smaller USB drive (8GB or less)
If you provide these details, I can look for a verified source for that specific file. To help you find a or specific Service
To help you find a or specific Service Menu codes : What is the current issue with the TV? Do you have the full board number (e.g., CV688H-A)?
Place the file in the root directory (not inside a folder). The Flash Process: Turn off the TV and unplug it. Insert the USB drive. Hold the Power button on the TV panel. Plug the TV back in while holding the button.
If the image is flipped after flashing, you may need to enter the Service Menu (usually Menu + 1147 ) to adjust the Mirror settings.