I’ve encountered this issue on my Razer Blackwidow (simple, not the ultimate version).
The letters “A”, “T” and a few others didn’t worked at all. I would press the letters but they would not appear on the screen as pressed.
The fix for this issue is funny but it worked.
Just lift the keyboard and shake it up and down for about 3-4 seconds.
After that, my keyboard worked again.
I’ve tried to reconnect the USB connector into the PC, tried to connect it on my laptop but that didn’t solved, the letters still didn’t worked.
Hopefully the issue won’t happen again.
I also spilled some Pepsi on the left side of the keyboard but only just a little and far from “T” for example. But I think it wasn’t because of this.
Anyway, leave in the comments if you have a similar issue and give us more details.