can anyone here enlighten me on step 5 about "2 flex cables joining the bottom board to the logic board" what does it really do? besides that? is it responsible for the digitizer to work? i'm having issues about my digitizer not working and my lcd w/ digitizer is fine. i'm doubting if it's the motherboard broken or the flex cables.

can you please enlighten men in step 5 about "2 flex cables joining the bottom board to the logic board" are they also responsible for the digitizer to work?