Contact iFixit store personnel at support@ifixit.com. The parts they sell are genuine Google parts and come with a lifetime warranty.
I have to note here that based on just my own personal observations, it appears to me that Google seems to have a bit of a problem with the quality of their replacement parts. I have read about many cases where a brand new genuine screen did not work correctly upon installation, requiring a return and replacement.
This is not by any means a criticism of iFixit, as everything I've seen just reinforces my belief that they do their best to find and sell the best quality parts available. You would certainly think selling parts provided by the manufacturer would be the best you can get, but that idea seems to be challenged by Google.