1. Find and Download the camera's firmware https://pan.sohu.net/f/ODE4ODAsdWh1dWI.htm
2. Put the file in the root of your USB flash drive, plug it to the DVR.
3. If you can enter its GUI, login and upgrade it.
4. If you can not enter its GUI, connect the DVR to the router, accessing the DVR via web browser. Upgrading its firmware via web browser.
5. If can't enter its GUI and upgrading through web browser is impossible, then you have to contact your seller.