Hmm, what do you mean Broken? When I added my SSD and had to detach most of the cables one of them being the keyboard light connector and once the install was done long story short even though I thought I put the connector back in properly it would not light. I then tried a second time and had no issues. I was just wondering if thats the case for you.
So did it light up when you first got it?
I may not be able to help but i am sure somebody else who can is going to want more details to help fix your issue. If its truly broken I would not see why you cant use your warranty. Hope this helps.