Ensure your area isn't prone to power outages. A power failure during an upgrade can "brick" your device. How to Download STB Upgrade Ver 4.0.2 To get the correct file, follow these steps:
Ensure your receiver chipset (e.g., Montage, Ali, or Sunplus) matches the specific firmware build. Stb Upgrade Ver 4.0.2 Download
Go to Menu > System > Information on your STB to see your current hardware version. Ensure your area isn't prone to power outages