WARNING
This method is no longer available to users, as such you most likely won't be able to downgrade to FW 2 once you are upgraded to another version.
You can manually downgrade back to Firmware 2 if you experience any issues with Firmware 3.
This is done by putting the Handy into Safe Mode and using a hotspot with a special name to download the old firmware. When downgrading, the Handy will automatically look for this hotspot and connect without additional configuration.
Steps
Set up a Wi-Fi hotspot on your phone with the following credentials
1.1 SSID: safemode
1.2 Password: recoveryWith your phone nearby, plug your Handy to an electric socket while keeping the Action button pressed
When the LED pulses YELLOW, you are in Safe Mode and you can release the Action button
Press and hold the DOWN button until the LED begins to fade in a rainbow fashion. This means the downgrade to FW2 is in progress. The Handy will automatically restart when the upgrade is successfully completed.