One of the Benz MB SD Connect C4 customers feedback he came across white screen problem when install SD Connect C4 multiplexer.
Solution from OBDTool.co.uk:
MB SD Connect C4 white screen problem solution
1) Dismantle MB SD C4 main unit.
2) Check the pin cables inside the device. If they are not connected, you can solder it again.Or change a new one.
The problem will be settled.
Anyquestions, please feel free to contact our customer service.