Face ID dont work by Change the Frame

Hello,

sorry for my english, i live in Germany. I have Change the Frame from my Iphone XR, bevore the Face ID have Work well done, after the Repair/Change is dosnt work. I habe Replacement the LED Flash FLEX (with power sensor…) from the back camera but this not the problem or? I have check the flex from the Face ID is not broken or any else. By the first start has Face ID worked but for 1 Time, actuelly doesnt work. What can i do?

Thank you,

Robert