My home button, back button and recent not working properly.

Recently, my phone back button, home and recent key are not working like as usual. When I tap on it, the screen not respond, and when I tried to turning the "show touch" function on, it like I am touching the bottom of the screen, not the button. I already reset my phone with factory settings but nothing changed. Is this hardware problem? I'm planning to send it to customer services tomorrow because I just bought it for two months. My phone is ASUS ZenFone 3 max 5.5 (ZC553KL) using Android 6.0 Marshmallow.