I just have to say I'm really frustrated with the huge list of things I am required to send in before I can get a faulty battery replaced.  $169 batteries and I probably won't be able to get them replaced because I'm sure I didn't save any proof of purchase from last summer on a couple of extra batteries.  It's really too bad because I love my Phantom 4 pro and the Spark looks really cool too, but I don't think I'd buy from DJI again when they make it so hard to replace things that are faulty.

I sympathize with your frustration, the warranty period of battery is 6 months and charge cycle less than 200 times. The proof of purchase is essential for warranty.
Could you please contact you dealer to see if they will help get the proof again? We really sorry for the inconvenience that has been caused.
By the way, have you created case number for this issue?