error code 0xC004C008 unable to sign into windows after installing a new motherboard

Hi there, this is Marc. Thanks for reaching out to the community.

The error code 0xC004C008 usually appears when Windows detects the product key is already in use, which often happens after a major hardware change like replacing the motherboard. To fix this, open Settings → Update & Security → Activation → Troubleshoot and run the Activation troubleshooter. If your license is linked to your Microsoft account, you can select “I changed hardware on this device recently” and choose your current PC to reactivate.

If that does not work, you may need to contact Microsoft Support directly to reactivate your license: https://support.microsoft.com/contactus

More details are available here: https://support.microsoft.com/help/20530/windows-10-reactivating-after-hardware-change

Best regards,