I got a new Apple Card $500 from Walmart and it says this code has been redeemed

Hi, I’m assuming you got and Apple Gift Card and you’re not referring to Apple Card (a MasterCard credit card by Apple).

Here is a link to a support article the explains many ways to resolve the issue you’re having with your Gift Card,

https://support.apple.com/en-us/HT201195

At the end of the article is a link to contact Apple Support if you need further information or assistance.

I hope this helps.