Hi,
Please first check the settings under: Control Panel\All Control Panel Items\Power Options -> left pan: choose what power button do.
Choose "Shut down" behind When I press the power button.
If the settings is right, but the power button still do the incorrect thing, please export following registry keys from the computer which runs fine, and import to your own computer:
Make sure you backup your registry keys to avoid unexpected crash.
HKLM\SYSTEM\ControlSet001\Control\Session Manager\Power\SystemPowerPolicy
HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Power\SystemPowerPolicy
Post back the power log if the issue still persists, please run this command:
powercfg -energy
Post back the output of this command for our research.