Settings > Device Preferences > About > System Update.
If your TV still boots, you can check for official updates through the menu: Download ONIDA LEO43FIAB2 Software part01 rar
You will need all parts (part01, part02, etc.) in the same folder. Use a tool like WinRAR or 7-Zip to extract "part01.rar"; it will automatically pull from the other parts. Format USB: Use a FAT32 formatted USB drive. Settings > Device Preferences > About > System Update