A is a very important letter. I hope you are able to fix your key asap. Did you try removing the key? (just apply a little force and it will pop off. Usually pull up from the bottom of it). Then maybe you can look at it? Also, sometimes pressing SUPER hard on it a couple of times make the key start working properly again.. oh, if you take it off, use a little alcohol to clean it (just in case). if all else fails, you might need a new one. if its still under warranty, you can get a free one.