Hi @generalramm ,
Just verifying that you have correctly reassembled the laptop and when you turn it on etc and then have correctly shut it down that it turns itself on again at some point without you touching it, is this correct?
When it turns itself on does it behave normally until you shut it down again or does it act differently?
Are you sure that there is no corrosion.
Check the cable connection on the power button board (see p.57 of the maintenance and service manual) to make sure that there is no corrosion in the connector.
You could try turning off the laptop and if it takes a little while before it turns itself on, disconnect the power button board cable and see if it then turns itself on. If not then the problem may be on the button board.
You have to start somewhere with eliminating what the cause may be if you suspect corrosion and none is evident.
Be careful when working inside the laptop because the motherboard has power on it even if the laptop is off so don't slip if using tools etc and try not to touch anything that you shouldn't.