There is only one ribbon laying underneath the screen. The screen has only one connector. Those two have to be connected. That should be connected. You might ask the ulefone service department like i did. Very friendly and helpful people there! (service@ulefone.com) They did send me this after I asked them for a specific part I damaged:
Hello, you can buy it from etotalk: http://www.etotalk.com/ulefone-paris-side-buttons-fpc_p12085.html and you can choose the shipping method.