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I spilled coffee over my mac's air keyboard yesterday. The computer seems to work but the keyboard doesn't. The symptoms:

  • The laptop boots into the drive selection screen every time (alt key constantly pressed?)
  • The caps lock, arrow, enter, esc keys all seem to work
  • I can't enter my password at the boot screen. Some key-presses seem to be registered but obviously not the correct ones. For example, pressing the N key once doesn't show a keystroke, but pressing it twice does. It feels like there's some function/alt/ctrl/shift key that might be constantly pressed, but I can't tell which one, or make it behave differently by pressing those.
  • An external keyboard (either bluetooth or usb) doesn't behave differently
  • If I choose the guest mode, the computer will boot into the Safari only mode. The same thing will happen there - some keys will show wrong signs when typed in the address bar, and at some points the keyboard stops responding.
  • The external keyboard however seems to work in that guest mode.


  • Can you help me understand what exactly is the problem with the keyboard?
  • Can anyone think of a way to log in to the regular mode?
  • Assuming the keyboard is the only thing broken, can it normally be serviced on a Macbook Air?


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OS X contains an app named "Keyboard Viewer" which should show you a picture of a keyboard indicating which keys the system thinks are currently depressed. – username Jun 4 '12 at 15:47
Well, OS X doesn't load... – yoavf Jun 4 '12 at 20:34
My mistake, by "guest mode" I thought you meant booting into the Guest account. – username Jun 5 '12 at 7:45
up vote 7 down vote accepted

keyboards are 2 layers of plastic film with tiny electric contact, separated by a third layer of plastic film with holes on the spot of every single key. when you press a key, the top and bottom plastic are pressed against one another inside the hole of the middle layer, and the electronic signal going from the top to the bottom layer tells your computer that the key is pressed.

problem is: separation is the same as an average good quality book paper sheet, or maybe the same as the aluminum sheet that makes a soda or beer can. also, the electricity that goes trough your keyboard is extremely tiny, and sensors are VERRY sensible, so your air battery can lasts longer. So even if you have a single hair touching those circuits, your keyboard would "break" the same way it breaks when you spill coffee or whatever liquid; even after the liquid dries, the coffee and the sugar are probably still there "pressing" your alt key.

solution: (this will probably void any warranty) open your computer carefully, remove the keyboard, dismantle all keys one by one, separate the plastic layers with surgical precision so you don't cause any ruptures to the electric "wires", then wash everything with a lot of water and very little mild soap, take extra care to remove ALL the soap, leave everything to dry in the sun (you know electronic components don't like humidity, right?) assemble everything together with "just-washed" oil free hands (don't touch the inner part of the sensors now). Doing all this, if you have any luck your keyboard might work 100% again... or maybe you might make it stop working entirely, who knows? =)

if you have some money, then backup you computer, go to the applestore and tell them you want to buy a new keyboard, because you broke the current one. they shall give you a brand new (refurbished?) one, and charge you only the new keyboard. or they might give the same one back to you, who knows? haha.

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If the "n" key is only working after the second press, your option key is probably one of the ones shorted. Because option-n will activate the tilde mode, and the second press will give you an "ñ" character.

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