This community often hosts exact .rar files for China-made universal boards. Search their software repository for the specific "Samsung" branded USB file. Installation Instructions
Download the .rar file and extract the .bin firmware file (often named bin_v56.bin or similar) to the root directory of your USB drive. Flash Firmware: Turn off the TV. Insert the USB drive into the TV's USB port. Download V56 PB826 1366x768 Samsung USB rar
You can find the firmware file on these specialized platforms: This community often hosts exact