Hey, don't panic. That tab sure is a piece of fragile technology. I don't know who can repair that and a new logic board would be expensive. I have had success with those kind of broken tabs. You will need for this repair a pair of tweezers with an angle.
- Find a thin but stiff plastic sheet (like the one covering a new touch screen or LCD).
- Cut a small strip about a 1-2 cm. and only wide enough to fit into the connector. It must not be too long so it bends when the screen is in place.
- Insert the "3" cable and with the tweezers slide in the plastic into the connector on top of the cable. You should feel a little pressure since it should press and keep the cable in place.
You might have to experiment with the plastic thickness but once it seems tight it should keep the cable tight. Let us know how it works!