The TMDS CABLE IS THE Monitor Cable. You wont have any video if this cable is unplugged from the Logic Board.
If the chip that connects the TMDS cable to the Logic Board is still attached to the TMDS Cable, then this means it has broken off of the Logic Board during dis-assembly. You will need to buy a new Logic Board. They range from 15-50 dollars depending on where you purchase.
Good Luck