A red patch cable "solid strand?" is inserted into the smart jack port.
What is the pinout of the modular plug that is plugging into the smart-jack?
568-B (White/Orange, Orange/White, White/Green, Blue/White, White/Blue, Green/White. White/Brown, Brown/White)?
If so, your signals are on the Orange pair and Blue pair (pins 1&2 and 4&5)
Divide and conquer.
Remove the horizontal cable from the 66 block, so that just the red cable with the modular plug from the smart jack is terminated. Use a piece of 1-pair jumper wire to go from the Blue to Orange pair. Does the Red light on the smart-jack turn Green? If not, the red patch cable is bad.
If yes, reterminate the horizontal able, go to the far end, twist the Blue and Orange tips together, twist the Blue and Orange rings together, does the light go green? If no, the horizontal cable is bad.
If yes, Terminate the 568-B jack on the end of the cable, plug in your loop back plug, did the light turn Green? If no, the jack is bad,
if Yes, you're done.