Mi 4 navigation buttons

[HoangVG]

Edit: Found the problem. The bottom part of my mi 4 isn't working properly after dropping (post 2). Pls help
(Sorry for bad English)

 

[HoangVG]

Omg it's the hardware problem. When i touch on the very bottom of the screen, it responses but wrong position ( i see it when i turn on show touch position like in the screenshot). So the bottom part of my phone is not working properly. Can this be fixed guys ?