Home Assistant gives Shelly devices running unsupported firmware a way to update without first completing ordinary setup. Instead of stopping at a setup failure, the connection exposes only its firmware updater and raises a repair that starts the update.
When the device reports supported firmware, Home Assistant reloads the connection and adds its normal controls and readings. The contributor tested the path with a Shelly 1PM running firmware from 2019 and a Shelly Plus Plug S running a pre-1.0 beta.