"This device is already linked to a user. Factory reset the device to change configuration." You may get this message when you try to set up your Google Nest or Home speaker or display, or Chromecast, or when you try to change the device’s Wi-Fi settings. This error message can happen if the device was used before, but your account isn’t linked to it.
What to do
To set up the device or change Wi-Fi settings, you’ll need to factory reset the device.
Important: This action will clear all personal data from the device and can't be undone.
Why the error message happens
Google Nest has put safeguards in place to help protect user data. If someone else previously owned a device, Google wants to make sure their data is removed before a new person starts to use the device.