From the help page here:https://help.corsair.com/hc/en-us/articles/360025465031-How-to-Reset-your-keyboard
This worked for me:
How to: Reset your keyboard
For all other keyboards:
Unplug your keyboard.
With the keyboard unplugged, hold down the ESC key.
While holding down the ESC key, plug the keyboard back into your computer.
After about 5 seconds, release the ESC key. You will see the keyboard lighting flash if the reset is successful.