MBA bricked by water damage – test whether just keyboard broken? Some drops of pure water were sprayed on the keyboard of my 2010 MacBook Air. I immediately tried to dry all of it with a cloth, then turned it upside dow, but open, an put it near the heating, so the rest could dry as well. After a few hours, I tried if it still worked and it did, except that the Alt key was electronically stuck, i.e. always treated as hold down. I tried a reboot, with the power cable connected, which also worked fine, but I could not log in, likely because the key was still stuck and thus my password was invalid. I let it dry some more with the lid closed. When I next opened it, however, the computer would not turn on at all. This has not changed after three more days.

I fear that something important short-circuited, but I still hope that only the keyboard is not working, including the power key. Is there any way to find out  for sure before opening up the case?
You could first try to reset the SMC, which you can find out about here.  If you the LED indicator on your MagSafe charger does not change, then you can assume that at least the keyboard is broken.  It really would be best to open the case and either reconnect the battery or inspect the keyboard's connection to the logic board.