Enter service mode (Turn off TV → Press INFO → MENU → MUTE → POWER on remote). Here you can reset NVRAM, but do not change numeric values . Wrong changes can permanently destroy the main board.

Disclaimer: This guide is for informational purposes. Firmware updating carries inherent risk. The author is not responsible for any damage to your television. Always use official manufacturer files when possible.

You need to know what version you are running to confirm the update worked.