That’s a kind reply from another seller about sitting back and relaxing, but honestly the best thing you can do is to sell 100+ items FAST.
Honestly people do get banned for life in your situation because it’s as simple as you are making Amazon very little money on 8 sales in 60 days and now they have a customer disappointmented enough to file a chargeback. Just their expense dealing with the problem can cost more than you make them, so the fact that you also could have lost profits for life from a customer that may no longer buy on Amazon they don’t take it very lightly when you’re a very small seller. (It’s sad, but the reasons above are valid. Picture 1,000-10,000 small sellers a month souring a relationship with an Amazon customer).
You probably did everything right, but Amazon has no way of knowing if you sent a perfect condition item and to the right address, etc. (If you have cameras and a tracking that shows the full address and not just a zip code that could help, but again it involves lots of time for Amazon when it’s much easier to see 12.5% defect rate, 1 chargeback. 8 sales in last 60 days).
There are relatively cheap items that sell 100+ a day on Amazon that you can break even, make a small profit, or only loose a little money on; so it’s up to you how bad you want to increase your chances of not getting banned.
There’s sellers with 100% positive feedback and much more than 8 sales in 60 days who get banned for life because of things like 1 day they cancelled all orders and had a 12.5% defect rate so I’m not just being negative!