Hi @chen hui
Thank you for posting this in Microsoft Q&A.
I understand that when try to register hardware in partner center, it shows "The Microsoft Entra tenant you are signed in to (xxx@xxx.onmicrosoft.com) is already associated with a Windows Hardware Developer Program account.
Please raise a support ticket for the issue you are experiencing via this page
https://partner.microsoft.com/en-us/support?stage=1
Hope this helps. Do let us know if you any further queries.
Thanks,
Navya.
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