Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hello Zoe Hung,
I understand that your computer’s motherboard was replaced, and Office 2021 now shows that the product key has reached its maximum number of activations.
Please try calling the current Hong Kong Product Activation Center at +852 3002 2858 to see whether it works. Keep the Office Activation Wizard open, as you will need to provide the Installation ID shown on the screen and then enter the Confirmation ID you receive.
Reference: Telephone activation is no longer supported for your product" error when activating Office
If the call does not connect or the activation is refused, please contact Microsoft Supportfor further assistance. Since this is a user-to-user community forum, we can only share suggestions based on our findings and personal experiences, but we cannot verify the license or reset the activation limit.
When go to support page, enter a short description such as “Office 2021 activation limit after motherboard replacement” select Get Help, then scroll down and select Sign in to contact support (please sign in using a personal Microsoft account). After that, follow the on-screen prompts to reach Support Team. It is recommended to have your product key, proof of purchase, and any motherboard repair documents ready so the support agent can verify the license and advise whether it can be reactivated.
Tip: Support chat availability may vary by country/region, product, and support hours. If you can't get in touch with a chat agent right away, trying again later or at a different time may help.
I hope everything goes smoothly. Thank you so much for your patience!
Best regards.