Why does my lg g4 turns off as soon as i pres the back buton

[AC Question]

Sometime knock feature(double tap on the screen) doesnt work , and even worse , when i pres the back buton as soon as the screen is turned on , turns off again in i millisecond(without me even trying to put a password , it turns off) ..i dont know what to do

 

[belodion]

The double-tap feature is not always reliable.

There is normally no need to press Back after waking the phone, but if it troubles you, see whether it persists in Safe Mode. It could be a third-party app causing trouble.