Did you replace the "Full Assembly" or just the front LCD?
If you replaced the full assembly (and transferred over only your TouchID) you most likely have a faulty TouchID Ribbon Cable that runs behind the LCD Shield Plate. You can swap over your original and it should restore functionality.
If, however, you replaced just the front screen you most likely damaged either your TouchID sensor or your TouchID Ribbon Cable that runs behind the LCD Shield Plate. You can replace the LCD Shield Plate and restore functionality, but you cannot restore functionality by replacing the TouchID sensor without Apple's assistance.