The most likely reason that the machine wont boot is that the coffee shorted the keyboard through which the power button runs. You have to open the machine and look inside to see if there is corrosion, shorted (burn marks) components or swollen (damaged) parts.
Start by studying the proper guide and notes (not just looking at them). Obtain the recommended tools - every job is easier when you use the proper tools.
At the worst you'll need a logic board and a top case... at the least a top case and good cleaning.
Follow the tags at right to see the sorts of things that can be wrong, and what to do to repair them.
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