a and c keys not working on macbook, even on an external keyboard It's a 2011 MacBook pro and the a and c keys are not working on both the built-in keyboard and the usb keyboard. 

Because of this i can't bypass the firmware login screen. 
Now the weird thing is that that cmd + a works (select all) so the key is being recognized, but a by itself doesn't. 

Any ideas?
You can start by rebooting into safe mode as a troubleshooting step. Restart and hold down the shift key, when booted into safe mode you can test the keys:

Delete the preference file which can be found here  /Library/Preferences/com.apple.keyboardtype.plist

Restart normally