Well... reset, set up again and if that doesn't work, maybe it's because the power supply doesn't deliver enough current. I recommend using the original power supply from netatmo, then it will definitely work. It was the same for me...

Difficult to give an answer with this info!? It is clear that the module never goes into installation mode with a green flashing light (which does not change to a steady green light). Have you installed and set up the Home App, which is absolutely necessary for the installation? If not, make sure you do so beforehand and then reset the bell again and start the installation again via the Security App. For me, it helped to run the bell on the USB cable near wifi during installation! The bell is extremely susceptible to weak WiFi and only works with a 2.4Ghz network! The automatic update function is now also available in the Home app - it is mandatory to activate it and all smartphones/tablets need the latest update (Apple).