Clicking the button to "Sign In" to Microsoft account immediately returns an error:

"Failed to login
We tried to sign you in to your Microsoft Account, but something went wrong"

The same occurs with four brand new Kindle Fires that were opened for Christmas this morning. Nothing unique to any one device, they all have the same error.

Note, this issue does not occur on old Kindles that are being replaced. Kindles running Fire OS 5.6.8.0 work just fine. But the new Kindles, running the latest OS, see this error.