Dell Precision 5560 will only powered on by plugging in, will not power on by pressing power button.

I have Precision 5560 i9 version. My laptop will only powered on by plugging in the power cord, It will not power on by pressing the power button without power adapter attached. So, without power adapter attached (battery only) it will not power on by pressing power button. But that doesn't mean the power button broken. The power button actually works..

scenario 1: plug the power cable -> turn on instantly

or sometimes like this

scenatio 2: plug the power cable -> press the power button -> turn on

But most of the times is scenario 1

I know that there is bios setting called "Wake up on AC" and the setting is enabled. I am afraid if I disabled the setting (which mean to turn on by pressing power button only), I will not be able to turn on my laptop completely since the power button will not always works..

please help

Thank you