FaceID not setting up

Recently I got my handset’s back glass & screen replaced as they were shattered in drop, but whenever I try to set up my FaceID the only message that pops up is move your head little lower/higher . Even the portrait mode of front camera is not working not only is it not sensing depth but lighting would remain the same in all in it’s modes . None of the parts of FaceID assembly have been replaced, Animoji , Attention awareness features auto brightness are fully functional. Just really cannot troubleshoot as to to where the problem may lie as replacing FaceID parts wont be doing any good . Before repair FaceID not available was the message that used to be displayed while trying to set it up but now it had changed to move your head higher/ lower. While trying to look at the sensor array with my camera only a single infrared led lights up very dimly on the left side of ear piece . Has anyone had the same issue & found solutions to it ?