I had this problem where the keyboard started typing seemingly random characters. What I found was that in the keyboard settings of my Macbook it was identifying the keyboard as "Razor Deathadder Elite" which is a mouse. As soon as I switched it back to Corsair K70 everything was back to normal again. Might be worth checking in your controls what the operating system is identifying your keyboard as.
I use a switcher to switch my mouse and keyboard between my PC and my Macbook and I guess it just got confused somewhere.