Wait for the "Software Updating" screen to appear. Do turn off the power until it finishes.
The specific firmware for the Android board with a 1920x1080 resolution (REF29) can typically be found on specialized LED/LCD TV repair communities. Because these files are often split into multiple parts (like "part2.rar"), you must download all parts to the same folder before extracting them. Firmware Download Resources Kazmi Elecom : This site is a widely cited source for the TP.MS338.PB801 Download MS338 PB801 1920x1080 REF29 USB part2 rar
software download , providing files specifically for FHD (Full HD) Smart TV boards. Wait for the "Software Updating" screen to appear