OK, first which GCS software are you using? If you still have the Openpilot GCS, then everything is fine. If you use the Librepilot GCS you will get a warning and need to be a bit careful. Do not change any values while running the Librepilot GCS on some old firmware. But it should be ok to take a look at some values.
So, now remove all your propellers from the quad. Do not go on if you did not do so. Switch your transmitter on, then start the GCS, connect your CC3D via USB to your computer, and power your quad with a battery, so that the receiver gets power. If all is fine, you will get a warning that your firmware is not up-to-date, and after a few second your controller should show up in the firmware tab.
If you get to that point, you can now go to the HITL tab, and try to move the sticks on your transmitter. The movements should show there (with a certain lag). If this is not the case, your connection between receiver and controller is somehow broken.
That should bring you so far as the supporter asked you to do. Please tell us your findings, then we certainly will get to the root of your problem.