Concerned with the age of the Samsung S7 replacement battery

Hello,

I just received my full kit to replace the battery in my Samsung S7. I have read reviews of many different replacement battery companies and there was a common theme: that the replacement battery was already a few years old and it never charged to the claimed capacity even though it was new, which was assumed to be because the batteries were old.

I noticed that the battery in my kit is just over a year old. I am a little concerned that it won’t live up to its claimed capacity. Can you give me some sort of assurance that it will actually be as good as new?

And also is there any sort of warranty on the battery? Thanks.