fingerprint sensor not working

Hi try clearing your cache partition

Goto, Settings> Biometrics and security> Finger prints, and remove all your finger print data and register your finger again.
During registration, whenever it says to change the position, then place your second (preferred) finger. Complete the registration. You can now unlock with any of your both fingers. This is an update bug and this is the fix.

hello! a5 fingerprint sensor are not much like than the s series. their technology is different.. i right now have the note 10lite and has the same fingerprint technology like the a51. i commonly face issue in sunny areas where fingerprint is not recognized. try to put the phone on dim area to scan properly

Hey there,

Please visit the nearest service center for them to be checked by our team.

https://www.samsung.com/ae/support/service-center/

Thank you