Hello

No, there will be no problem at all with your biometric at the JEE exam centre.
Biometric verification is done through your fingerprints and photograph, not your mobile number.
You can freely change the mobile number linked to Aadhaar it does not change your biometrics in any way.
Just make sure your name, photo, and Aadhaar number are correct and clearly visible. Carry your admit card and a valid ID, and avoid (mehndi or oily) other activities on exam day.