Release the button when you see the "Software Upgrading" progress bar on the screen.
If the update doesn't trigger, try a different USB port or a different brand of flash drive. Community Insights Download MS638 PC822 3840x2160 Aconatic 49DSU800 part4 rar
If the image appears too large (oversized), ensure the config file matches your 3840x2160 panel resolution. Release the button when you see the "Software
If the TV hangs on the Aconatic logo, the firmware might be incomplete or the internal memory (eMMC) may be failing. Download MS638 PC822 3840x2160 Aconatic 49DSU800 part4 rar