Macbook water damage

Hi,
I have a macbook late 2008 version (white one).
Couple years ago, I had a problem with airport card being missing, but still present in the computer. The software couldn't find the airport card.
I got it replaced, and the same problem started again.
I accidentally spilled some water on my macbook, and ended up drying my macbook in the air for couple days before restarting.
My computer starts just fine, nothing lost, all hardwares working fine except the airport card being lost again..
I'm not so sure if it's from the water damage or the same problem.
However, I took it to the genius bar and they stopped diagnosis immediately after figuring it out that there was water in the device. They need to charge me more money to even figure out what part is broken because it's water damage..
Is there anyway that I can do the diagnosis at home and part out my macbook?
Thanks in advance.

The only thing you can do is run the Apple Hardware Test. But even it if it comes back and says your airport card is not working, would you be able to change it out yourself? Also consider your MacBook is a 2008 model. Might be time to consider buying a new computer rather than spend money on repairs.