1. Connect pc and box with rs232.
2. Open GX6621_16MB_Download_V1.00.exe pc tool.
   1)Serial Port:select the right com port
   2)Mode:select "serialdown"
   3)File:select right file to update(should use upgrade file)
3. Press "Start" on GX6621_16MB_Download_V1.00.exe tool.
4. Power on the box, it will auto download sw and try to burn to flash.
5. After it finish the upgrade, power off and power on box.
