Samsung freeezes and home buttons don't work

Samsung freezed and become unresponsive. No button was working. I forced powered off to restart. After restart i restored factory settings and still was unresponsive. I switched it off and after a while become responsive.

I tried to check wifi connection but it seemed fine.

Smth does not convince me, as it seems smth wrong with this tablet. It is still under warranty and i cant decide if is smth related to hw or sw. It has the version 4.4.4.

Does anyone faced similar issue?