Keeping your updated is the best way to extend the life of your television. Always double-check your board number before flashing, and never turn off the power during an update.
Try a different USB port or re-format the drive to FAT32.
Search for your specific Mainboard Number + Firmware to find the exact .bin or .pkg file. Step-by-Step Installation Guide (USB Method)
Go to Settings > About or System Info . Look for "Build Number" or "Model."