I've had a negative Amazon review removed because the seller reported my review. I was able to submit a new review that was not removed, after contacting Amazon support. Also, when I contacted Amazon support they explained why my review had been removed, which I found very helpful. Here's what Amazon support said:

Hello Nathan, I apologize for the confusion you experienced in this case.​ We encourage customer content on the Amazon.com website, both positive and negative. However, your recent contribution doesn't comply with our content guidelines. Specifically, your contribution contains comments related to the seller and not the product itself. I'd recommend submitting your review again, restricting your comments to the item. For your convenience, I've included your original Review below: The battery I received did not work at all. I returned it for refund. The seller was responsive, and offered me $10 to remove my bad review. Please take a look at our Community Guidelines for information about acceptable content: https://www.amazon.com/gp/help/customer/display.html?nodeId=201929730 If you'd like to leave feedback for the seller you ordered from, visit this page: http://www.amazon.com/feedback I hope this helps! Best regards, Alice Y.

Note my original review from above:

The battery I received did not work at all. I returned it for refund. The seller was responsive, and offered me $10 to remove my bad review.

I feel that mentioning the seller in this way was very relevant, but I guess Amazon disagrees. The positive reviews also mentioned the seller, but of course the seller didn't complain about those. I then asked Amazon about the double standard but they ignored me:

Hi Alice, Thanks for explaining that my review was rejected because I mentioned something about the seller. However, notice that these other two reviews of the same product also talk about the seller: https://www.amazon.com/gp/customer-reviews/R1SUR5G7FDAO80/ref=cm_cr_dp_d_rvw_ttl?ie=UTF8&ASIN=B01I1IY1SY https://www.amazon.com/gp/customer-reviews/R3GVDST5W3UDEM/ref=cm_cr_dp_d_rvw_ttl?ie=UTF8&ASIN=B01I1IY1SY Why are these reviews allowed and mine is not?

But at least they didn't remove my updated review:

The battery I received did not work at all.

Maybe you could contact Amazon support and find out what technicality allowed the seller to have your review removed?