Trackpad/Keyboard wont work, minimal water damage to hardware

Alrighty so my trackpad and keyboard wont work, it's sort of crazy how this happened because theres obvious water damage, and nothing ever spilled on my laptop! The apple store confirmed my theory as well. If you familiar with the guts of the newest macbook pro, the logic board is separate from the chip in question. The water damaged circuit board is located center and bottom below the battery. The apple store has a flat rate to fix any hardware issue of 750 dollars which seems absolutely ridiculous. Im using the laptop right now with USB peripherals. I believe now after some research that the circuit board in question is the back side of the track pad. would this make the keyboard not work as well? is the keyboard "hardware" located in the logic board? I really hope not. The apple store guy said that i would need a whole lower case replacement (battery, keyboard, track pad, etc.) but I refuse to believe this. Also would anyone recommend fixing this myself? if I can narrow out what could/should need replacing it will save me a lot of money and frustration. Also I might add that the force touch track pad isn't working properly is a mechanical sense. Its not clicking and feels gummy like a rocks under it or something. Thanks for your time guys!