Tank you,
I was too eager to get it working and was probably trying too hard. In the end my device died on me. As it seems one coil (USB power L7) and power stabilizer (U15) for 2,8V have gone bad probably because I used the same computer for power and serial connection. Looking at the schematics, that was probably a bad idea. Accidentaly shorting the pin 1 on CN7 durring programming would explain things too, but i have taken precausions for that, so not sure. I don’t know if I will be able to recover this device, but probably not. I managed to make a full system backup (although it’s the corrupted state) if anyone is interested. I also confirmed that I was able to restore to that state comletely. My plan was to rewrite all available parts of it and flash it back. With this, I would probably get it working. A little more patience would help. 