@tinnywoo
We don't have a battery doorbell, and have not had an offline problem with any of our Google Nest cameras and doorbells.
You could try a simple "Restart" (not a more drastic "Factory reset") on your battery doorbell:
https://support.google.com/googlenest/answer/9252162?hl=en&sjid=7543293783608498098-NC#zippy=%2Cnest...
Or you could wait for a response in this forum from someone who has resolved an offline issue with the battery doorbell.
Or 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.)
5. Under "Contact options", choose to get a phone call or chat with the team, depending on availability in your country.
