Hello friend, Thank you for posting your question on Just Answer! I will be happy to help you with this problem. Can you please give us some more information so I can better answer your question?
there are no signal message on all inputs?
If you were to hook up a dvd player to all inputs and try it, with out the cable box and verify its all inputs then friend you will need a main board, this board is the board with all inputs.
These are some part stores, CALL THEM IF POSSIBLE always check with manufacturer, and you may need the name of the part and its part number off the part itself