On my MacBook Pro A1706, the touch bar worked before the keyboard replacement and stopped working after. After some debug, I found that under the corner of the motherboard that has the touch bar connector (near the hinge closest to the keyboard's "1" button) there is a short "elbow" ribbon cable with a small component (with a metal top) on the end that is meant to be flush with the back of the keyboard. This component was not sitting as low as it did before the keyboard replacement, so when the motherboard was screwed down, the metal top of the component made contact with something on the motherboard, stopping the touch bar from lighting up due to a short circuit. I fixed it by putting a small piece of tape (I used Kapton tape) over the component as well as on the motherboard in that area (you can see several gold test points there on the motherboard along with a couple of very small components). After screwing down the motherboard and reassembling, the touch bar worked like before.