That is because screen replacement isn't that easy.
The two cables on the top of the LCD units (one cable is for Digitizer and the other for LCD Data) are very very fragile. If you bend them too much you will break them and cause them to fail.
In your case you have bent the digitizer cable too much. The ifixit manual doesn't point it out much afaik and my friend screwed is digitizer lately the same way as most people do.
I cant find the exact video but here it's also said https://www.youtube.com/watch?v=wp8wv8TYBfI
@7:50 - there is also an 4S video for the disassembly that you might want to check out but he doesnt show that particular reassembly part where he highlights to be cautions . this particular step is the same for the 4S.
You have to ensure that the digitizer isnt squashed pull it all the way through and be careful when bending it.
Having said that , you will probably need to throw your LCD units into the bin because you cant replace the cable and need to order new Displays.