An update progress bar should appear. Do not turn off the TV until it finishes and restarts automatically.
Do you have the (e.g., TP.MS338...) or the Part 1 file already? Download IRIS SAT 42E790S Firmware USB part2 rar
Format a USB drive to FAT32 and copy the extracted file to the root directory (do not put it in a folder). General Installation Steps Power Off: Turn off the TV and unplug the power cord. Insert USB: Plug the flash drive into the TV's USB port. An update progress bar should appear