In very rare cases, GrapheneOS OS updates fail. This can be concerning for users when it happens, but the chances of a phone being "bricked" is very low.
GrapheneOS, as well as some other OSes, have changed or are changing updates to A/B (seamless) system updates. In a nutshell, A/B system updates was designed to accomplish two things: less downtime for phone users and fault resistance.
The update process looks roughly like this:
- The updater app checks for updates, finds one, then starts a download
- The updater app tells the
update_engineto update using the downloaded file - After the update is complete, the
update_enginechanges the boot slot - When the phone restarts it attempts to boot to the updated slot
- If unsuccessful, the phone will revert back to the old slot
Due to how phones with GrapheneOS installed perform updates, bricking a phone during updates is extremely unlikely. Restarting a phone or a phone dying during an update will not brick the phone. However, if a phone fails to successfully boot after an update multiple times, then that can be an indicator of failing hardware.
As of version 2023102300, users can now require the updater wait until the phone is charging to install updates. That can be set up in the Owner profile by toggling it on here: Settings > System > System update > Require device be charging.