Sounds like the liquid damage may have cooked the board. [br]
Generally these things happen over time, not always will a liquid spill finish off a computer instantly. [br]
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Alternatively, you may try replacing the I/O board and see if that solves the issues! [br]
I have seen a few of these machine not start with a bad board. [br]
Try unplugging the board and see if you get it to power up![br]
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Good luck!