Switch firmware and recover over USB

Use USB to change firmware families or restore a controller you cannot reach on the network. If the controller works and you only want a newer version, follow Update firmware.

On this page

Before removing the controller

Back up settings or save the ESPHome YAML if the controller is reachable.
When switching, choose your firmware and expect to repeat network and app setup.

Reinstall, erase settings, or change firmware

With power off at the breaker, disconnect CN105. Connect the controller to a computer with a USB-C data cable.
Open the firmware flasher in Chrome, Edge, or Brave.
Choose the firmware and review the warnings before installing:
- Reinstall ESPHome: The version supplied by the flash tool resets stored settings even when Erase everything first is unchecked. The install button says Reset and install.
- Update HomeKit-compatible or Matter-compatible firmware: Leave Erase everything first unchecked to preserve settings, unless the flash tool shows a reset warning for the selected build.
- Erase all settings: Select Erase everything first to clear the controller’s flash memory, including saved Wi-Fi details and pairings, before installing any firmware.
Install and wait for completion. After an installation that resets settings, configure Wi-Fi and pairing again using the appropriate setup guide.
Disconnect USB before reconnecting CN105, with HVAC power still off. Follow physical installation, restore power, and verify control.

Crash-loop safe mode

HomeKit-compatible safe mode keeps only Wi-Fi and the web interface running. Use the IP address from your router; .local does not work. The page shows a safe-mode banner. Update over Wi-Fi or use USB recovery above.

On Matter-compatible firmware, safe mode offers only the backup setup network and cannot install an update over Wi-Fi. Reinstall the firmware over USB.

See status lights for the yellow safe-mode pulse.

If recovery does not solve the problem

If USB cannot detect the controller, follow USB troubleshooting. If safe mode returns after reinstalling, check wiring and power, then collect diagnostics and contact support.