response

Hello, when I press the power button on my Redmi 4A, the display on and I can unlock it. But the touch-screen response only a few seconds. Then I must switched off and on again. The phone has not been damaged by water. Any suggestion? THX

Hey guys! Maybe somebody among you had this too. It happens frequently that I leave an app such as Whatsapp or Facebook open (not only in background but straightforward on the screen, as last thing I see before locking it), I lock the screen and then when I unlock it back there's no response...