Question HP Elitebook 8530W - Unresponsive Power Button

I purchased a HP Elitebook 8530P "for parts" and would like to repair it. The issue is that when I press the power button the laptop does not power on and nothing happens. The only light on the machine is the charging LED, which disappears when the laptop is unplugged.

However, if i unplug the laptop, remove the main battery, unplug the CMOS battery, and then plug it all back in, the laptop will usually (but not always) turn on. Upon turning on it will show a message saying that CMOS settings had been reset and asks if I want to enter bios to set time/date. I cannot enter the bios due to it being password locked. I am given the option to continue, and if i select that laptop will boot and function perfectly. I have installed an OS on it and am writing this forum post from this laptop.

Once the laptop is on, the power button still does not work to turn the laptop off. Pressing the button or pressing and holding does nothing. I have to either shut it down in software or unplug the power cord and battery.

What I have done:
Checked CMOS battery (reading 3v)
Reseated RAM several times
Replaced thermal paste
Ran the built in