Open the samsung members app, go to support bottom right, phone diagnostics. There's a test for device buttons. If that fails, then there is some problem, it it says it works, then, uhh, try a reboot? Hopefully it doesn't fail
First turn the phone Off and On i.e a Soft Reboot, but if that does not help then follow this by trying a forced reboot by holding down the volume down key and power button simultaneously for more than 7 seconds to restart it. When your phone resets, you will feel it vibrate.
If i can be of any further help please don't hesitate to ask 😎
