p20 dont response screen

i buy p20 lite. sometimes dont response screen when i want unlock, it shows lockscreen and not work screen to unlock even when swipe selected. i dont know why. i updated software from 8.0.0 152 to 180. i got 9 but dont installed. maybe fault phone? i have warranty. i see black screen and battery low 8% percent i see red color in battery when i see black screen when i try unlock and dont response to unlock, just shows lockscreen and screen goes black even when i tapping on screen, on lockscreen shows battery good, but when screen dont response to unlock, the phone goes sleep and when i try unlock dont response anything just shows screenlock, and when to try unlock dont unlock i see black screen on top bar and battery left 8% but not as the same on locksreen which exactly percent 78% on lockscreen, but when i try unlock and dont unlocking phone, it shows 78% when i press lock button i see lockscreen shows but when dont response i cant unlock i see quickly status bar and left 8%, just status bar not homescreen, and turn off screen, when i hit power button i see lockscreen 78 battery when restarting phone unlocking perfect, but the same issue repeated every day