Hold the on the remote while plugging the TV back in. Continue holding until the "Software Updating" message appears.
: If the firmware isn't listed online, you can email Hisense support with your model and serial number. They often provide a link to the specific .pkg or .bin file required for your board. Manual Installation Steps Download RSAG7 820 5819 Hisense 55K390 part10 rar
: Visit the Hisense USA Firmware Download or Hisense Canada Support sites. You will usually need to enter your TV's serial number to ensure you get the exact matching software. Hold the on the remote while plugging the TV back in
Power off the TV and insert the USB into a . Download RSAG7 820 5819 Hisense 55K390 part10 rar
Wait for the process to complete (usually 5-15 minutes). The TV will reboot automatically.