Unlock screen issue

Hi guys I received this phone some days before and I am having a lie issue and is when I try to wake up the phone with the finger print pushing the button or the lateral one. The phone is in black don't wake up if I touch the buttons I feel the vibrationsame but still off the screen and after several tune it wake up normally. And all work OK. I think no is a hardware issue coz normally it works fine but some time's ..Ido no is a big problem but disturb. Ty to all

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