Warranty on refunded apple goods?

Hello,
Some time ago, I had gotten my iPhone refunded from amazon via a refunder. Now the problem is that it's having an issue that I might have to go to an apple store to fix ( network issue).

So will the warranty still be valid? And if I tell apple my imei/serial number ..will they come to know about how I got this product?

I also have the same question for macbooks, if I take a refunded macbook to an apple repair store,will the warranty be valid, or will they know?As I don't have it's invoice.

Any help would be appreciated & and if any of you have taken their refunded goods to apple ..let me know.