The fact is that very few people (if any at all ) know what all the criteria for getting the buy box are. I strongly suspect that it is completely controlled by AI robots. I also suspect there are some random factors thrown in which make it completely impossible for sellers to understand what's going on. in my opinion this is why there are hundreds of posts in this forum asking the same question as you. Nobody as far as I know has been able to answer the query. Personally I cannot believe that poor feedback is not taken into account but then Ive been wrong about the buybox in the past. There were 2 things I was absolutely certain I knew about the buy box . The first was that if you wern't a pro seller you automatically didnt qualify for the box. The second was that in the books category (which is what I sell) "condition" trumps everything (including price, delivery time, feedback etc) . I have recently seen quite a few examples that prove me wrong on both counts (although "condition" still seems to be the top consideration)

To sum up : everyone on this forum that gives an opinion on what you should do to get the buybox probably does so in good faith but nobody knows for certain