820-3115 Won't power OFF

[Sam A]

Had water spill and would not power on. Most corrosion was right around SMC IC U4900.
After cleanup powers on automatically when battery attached, or without battery attached powers on when adapter connected to DC jack. This is with or without keyboard connected.
When on, system boots and functions normally.
Only turns off/stays off when power button is HELD down. When power button is released, system turns on again.
Having trouble figuring out what is shorted on.

 

[dukefawks]

I would say corrosion under the SMC. Add some flux and some heat to try and clear it out. Do not fully reflow the SMC, just 150C.