You should be able to manage your device @ https://connectzbt1.home-assistant.io/firmware-update/.
However, the web firmware update tool was disabled in September 2024 in home-assistant/connectzbt1.home-assistant.io@a110225 without explanation.
As of the last update of this site (November 2024), the official site linked above displays "The firmware update is temporarily unavailable". Subscribe to home-assistant/connectzbt1.home-assistant.io#137 for updates. Do not leave unproductive comments - use the emoji reactions to +1.
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Use this tool at your own risk.