The OP spilled something into his computer. That is what caused the damage. It's called being responsible for your actions.
For the record, I spilled a glass of whiskey into my old 2007 MBP once. Fortunately it didn't get on the logic board. I bought a new keyboard and replaced it myself and everything worked fine until I sold it a number of years later.
Did you take responsibility for your actions and tell the purchaser of your Mac about spilling a whole glass of whiskey on it?
Yea, I thought not...
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find someone at your school who is handy and a day doing it. A damp rag with distilled water
Coffee stains shouldn't be that damaging just wash it off with clear water.
Why recommend water over pure alcohol?
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The OP spilled something into his computer. That is what caused the damage. It's called being responsible for your actions.
One other point, whilst the OP spilled something on the computer that doesn't discount the possibility of the technician being negligent during their assessment. I'm not sure why you would think this is automatically the case.
If someone told me they had spilled something on their machine, no way would I try and start it up without doing an internal inspection first.
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Your liquid contact indicators are definitely tripped, no amount of cleaning is going to undue that.
Where are they on his MBP?