Thanks a lot, I was almost there! I tried the UIflow firmware. The configuration button gave me an error. The burn asked me to connect to wifi. I asumed that it was the wifi of the m5, but thought that it would not work because the core was without OS. After your suggestion I unboxed the Core again (it was ready to send it back ;-) And now up and running again. Many thx ;-) Hopefully after the update the env II sensor wil work now. Because there the troubles started. Out of the box it did not work. Now i will retry.