P751DM2-G Automatic Boot? Problem with power button?

Hi guys,

I have P751DM2-G (i7-6700K and GTX 1070) and I have a strange problem with the laptop.
It can randomly automatically starts/reboots either when it's plugged or on battery.

Sometimes power button doesn't work, sometimes it can boot to Windows, sometimes performs restart after the POST and sometimes reboots even in BIOS.

The most stange thing is that sometimes it boots normally and I can play games for hours and everything works fine but sometimes it boots and boots and boots again.

Here are some videos of the problem:




It looks like the power button was pressed even if it wasn't pressed.

 

Probably just disconnected cable between power switch board and MB. One end should be visible under keyboard.

 

Check that first otherwise you may need to replace the power button board.