Hello friends

I am remote in northern Norway right now and its not easy to get professional help here. I had a flat rear tyre yesterday but managed to get that fixed.
The problem now when I have put back the wheel on is that the rear brakes hardly works at all. The rear brake lever "bottoms" when braking but theres just a little of braking happening. All the mechanical parts seems to be where they should and the brakes are working, just way to little. What could could be the problem?

I have tried to see if it was air in the system and aired out a little but it didnt get better......any suggestiones?

Thanks in advance!