[Whitewolf7789]

What do you think I should do?

Sony does have the capacity to blacklist serial numbers. It may not happen, but there Is a (remote) possibility that It will.

You can either risk It, or say your brother took the PS5 In your absence and told you about It at a later time. Then return It for a legit refund, and order It from another company that doesn't tend to take action. - Amazon being the obvious choice.

What is the point of buying through Amazon? As long as there is a third party seller, they will brick it.