Right now, Notion will not work if your power goes out. You will receive an alert as soon as the bridge has disconnected from our servers. This can of course happen for multiple reasons: power outages, loss in internet, signal issues, or the bridge being unplugged.
Our team is constantly working on updates and improvements to Notion. With future revisions of the bridge hardware we hope to include the option of cellular data connectivity with a battery backup in the bridge. This would allow Notion to operate for a short time if your power goes out.