Dear Samsung Member,
Greetings from Samsung Customer Support!
Please perform the below mentioned steps to resolve the issue:
1) The device may not recognize fingerprints that are affected by wrinkles, small or thin fingers.
2) To improve recognition performance, register fingerprints of the hand used most often to perform tasks on the device.
Please visit this mentioned link to resolve your device heating issue: https://www.samsung.com/in/support/mobile-devices/why-the-device-heats-up-during-use/
For further assistance, register your concern in Samsung Members Application (Open Samsung Members Application > Get help > Send Feedback > Error report/Ask questions).
Thank you for writing to Samsung.
Samsung Customer Support