How to fix water damage myself!

A very small amount of water splashed on my macbook pro - less than 1/4 cup - I’m thinking like 1 1/2 tbs…turned it sideways, probably bad move then turned upside down for 3 days. Spent 2 hrs online with tech - it only turns on in recovery mode but unfortunately doesn’t show hard drive or allow any of the other options to be used (wipe it, reinstall Os X etc) Took it to genius bar and this is what they said: Ici is tripped, they removed SSD and noticed small amount of corrosion on the main logic board. Now all this is foreign to me but plan to have a friend fix it or help - how easy is the fix? how do we go about it…any suggestions helpful!! how much would this all cost?