I’ve found this Kinetos-auem branch in Github, build image and flashed it. but same as before.
I found out, you was right. It is no rccb. It is an RCM (Residential Current Monitor) 14-01
And the CT Sensor ist CT303
Current measuring is built in Atmega firmware, that you will probably have to flash too. You will need a programmer for that. Hopefully, they haven’t fiddled with hw design too much. Seems that Kinetos have made tens of variants with zero contribution to the opensource base.
Heureka…found the problem. It was a bad crimp at the jst connection.