Button stuck (but not physically stuck?)

[Corksean14]

I'm suddenly having a weird problem with my Retina MBP - the 'a' button seems stuck, but it doesn't seem to have anything to do with the physical button itself...

the accent bubble that comes up when you hold down A is constantly appearing in any text boxes, and when I'm on desktop there's a continuous rapid beeping that I assume is to do with it trying to tell me there's nothing on my desktop to be highlighted by pressing A. the button itself felt normally clicky, but I pried it off anyway to see if there was anything stuck under there - the scissor mechanism and membrane all seem fine, nothing stuck or sticky. Issue remains, which is worrying me - I have exams in a month and I need this laptop to be working. Rebooting and updating didn't solve the problem either, just made it difficult to log back in as for a while it kept filling the password box with a's, but it stopped after a minute and let me type.

Any ideas?

 

[DeltaMac]

I think you have a sticking key.

You can find out very easily by going to System Preferences, then Keyboard.
Click "Show Keyboard, Emoji, & Symbol Viewers in menu bar. If you DON'T have that option, click on Input Sources, then Show Input menu in menu bar. Both would get what you want, which is a new menu near the clock, which gives you a choice to Show Keyboard Viewer, among other choices - choose Keyboard Viewer...
And, you will get an on-screen echo of your keyboard. You can press each key on your physical keyboard, and each press (and release) will be reflected on the screen keyboard. You will quickly see if your A (or any other key) is sticking.
You want to see if the key is pressed, and then shows a release as soon as you release it (without a delay of any kind.)

Press & release each key, you will see sticking (or non-working) keys now.
If you have a hanging or slow key, you can try banging on that key a few times. Give it a good workout, and you may get that to function more reliably - or it gets worse (because it is time to replace your keyboard.)