I dropped my MP3 player when walking through a forest once. It survived 14 hours of being constantly rained on in the mud and worked perfectly afterwards. That's what I get for having a Samsung instead of an Apple.
Fun fact: Most computer components can actually go through a dishwasher with little ill effect. If you spill liquid on your computer, immediately remove the battery and cut power. The liquid itself won't hurt shit as long as there isn't a current running through it. Let that shit dry completely and I mean completely before attempting to power it back up again.
You might be double fucked because you spilt tea and not just water so the inside might be sticky for a while which might gum it up worse.
Continue letting it dry. It's a less expensive option than taking it to a technician, and if it's really dead than an extra day of waiting won't make it deader. Unless you really need a computer right /now/ in which case you're gonna have to talk to someone about it. You mentioned it wasn't yours so you might have to have the school just take it back.
Stick it in a bag of uncooked rice but don't get your hopes up, my Macbook Pro did not survive water and they're a lot tougher than a flimsy Air. Don't be alarmed if your keys start to bleed pink, that's Apple's spill-detecting ink packets exploding which will alert any Apple Genius that you are a clumsy wumbsy and voids your warranty completely, they won't touch it once the ink packs go.
Yeah, even as a Macaboo I was like "Awh fuck you guys" when I found out that, no, my Macbook was not bleeding blood in some magical Christian miracle but just a really typical Apple grab at fucking you over.
Seriously? They void the warranty for that, and isn't the warranty / insurance bought in case of that. .-.
Stupid apple, making all the expensive crap unable to be fixed without spending a fortune. And this i why I have my 450$ windows butt laptop we've been keeping alive longer than it should be through tons of bluescreens by switching the memory a lot OTL.
You don't TRY to turn it on, you're sending electric into damaged circuits. You leave it to dry, and hope that in a week it will turn on, but because you keep turning it on, you may of already done nasty damage.
I hear placing electrics in a bowl of rice can help to absorb the moisture.