I dont think it is restricted to a batch, it seems to be an issue with this model. The first time my keyboard had an issue it was replaced, I am still awaiting a reply from customer service after I contacted them regarding my replacement also developing the issue
Now my replacement keyboard also has dead LEDs. If any of you here are thinking about buying this - do yourself a huge favour and avoid purchasing a rapid-i. CM also doesnt seem to give a crap about this keyboard. Again - please do not purchase this keyboard - for your own sanity. This is the second one with LEDs dying on me. It is clearly a major issue and CM is refusing to acknowledge it.