Finger print sensor

Brother, please remove all your fingers and re-insert your first finger. However, this time, please enrol both your hands fingers/thumbs under one finger enrollment.

Done that already. It is not responding to my finger at all

Check to see that there are no issues regarding your screen protector.
Ensure that the screen protector or the touchscreen on the fingerprint sensor area is not scratched or damaged.

Screen protector
If your screen protector is smeared with dirt or other foreign substances, scratched, or otherwise damaged, it may affect the fingerprint recognition performance of your phone.

screen protector placed correctly
If you're using a 3rd party screen protector not authorized by Samsung, its specific pattern (dot, grid, etc.), thickness, or material may affect the fingerprint recognition performance.

Check the following factors that could potentially interfere with your fingerprint recognition.
Your phone's fingerprint sensor may not recognize fingerprints properly due to various factors regarding the fingerprint or the surroundings. Please try again after checking that your fingers are not too dry, too wet, or if they are not fully placed over the sensor area.

Clean hands
place finger
Taking your finger off the sensor too quickly could be a reason why your fingerprints are not recognized. Please try again by placing your finger on the sensor for a longer amount of time.

Position finger
Placing your finger improperly over the sensor is another potential reason why your fingerprints are not recognized. Please try again by placing your finger over the entire fingerprint sensor.

correct finger
If your fingerprint isn't matching the fingerprint data on your device, please try again by changing the angle of your finger or by adding a new fingerprint.

Note:
We recommend registering your fingerprint in a position that feels comfortable for your finger to ensure that the fingerprint being read is identical to the one registered on the device. When re-registering your fingerprint, start at the center of the sensor and move toward the top & bottom, left & right.
You can set the fingerprint recognition operation in the off screen or AOD state as follows:

Go to Settings > Security and Privacy > Biometrics > Fingerprints > Fingerprint always on > Select your preference: [Off, Cover Screen, Main Screen (default setting), Cover and Main Screens]