A common source for USB firmware and eMMC dumps for the MS638 series, available at KenotronTV.ru .

Occasional Google Drive links are shared via technical communities like Advance Electronics on Facebook . Installation Instructions

Hold the button on the TV (not the remote) and plug it into the wall.

Format a USB drive to FAT32 . Copy only the extracted firmware file to the root directory of the drive. Flash: Power off the TV and insert the USB drive.