MBA only powers on when plugged in but then works on battery.

I spilled an entire cup of coffee on my Macbook Air. I turned it off instantly and dried it with a fan; I was out of town and had to wait until i could get home and open it up and clean the components. Other than the mic, it seems to be working ok except for one thing- I can't get it to power on unless I have it plugged in and I hold down the power button for several seconds. Once it is on and I don't let it go to sleep, it works fine on battery and the battery life seems unaffected. If it is asleep for any amount of time, I can't wake it up like I used to from sleep by pressing spacebar or clicking the trackpad, it needs to be plugged in and I have to hold the power button down and it totally restarts. Is this a power button problem and I need to replace the upper case? Or is it something else? It seems like the power button is working somewhat because obviously it starts the computer if I hold it down while plugged in; I am just confused about why it is behaving this way and want to replace the right component(s).

Thanks, I appreciate any suggestions!