Ask HN: How to redeem a gift card without risking lock-out?

My young daughter got 2 Amazon Gift cards for her birthday, but they look like they've been tampered with. I would like to check whether they are valid or not without having to go through the redeeming process: I want to avoid being at the mercy of a fraud detection algorithm that may lock me out of my account. There was a HN story not too long ago about someone who got locked out of their iCloud account for similar reasons, and the risk doesn't seem to be worth it to me. Surely, I can't be the only one with this problem. How do people do this "safely"?