@thumpus123
Without some more specific details (such as, was the factory reset successful, as described in the Help topic), and what exactly is happening when you try to reinstall your camera in the Google Home app, it's hard to tell what's going wrong.
You could try contacting Support:
1. Go to https://support.google.com/googlenest/gethelp.
2. Select a category/product family, and type in a brief description of the issue, then click "Next".
3. Click "Other", then click "Next step".
4. Under "Resources", just click "Next step". (Clicking one of the listed links will bring up a Help page page.)
5. Under "Contact options", choose to get a phone call or chat with the team, depending on availability in your country.
