PowerBookMedic is correct! An independent servicer or you can't fix this.
If the sensor is broken you'll need to bring your system into an Apple Store or ship to Apple for them to repair it. Apple is the only one that can fix this.
Think of it this way this is a deterrent for someone to steal your laptop as well as offer a level of privacy. Just like your iPhone or iPad the TouchID or FaceID protects you.