I finally used a very small blade on the opposide point to the spudger on the picture. There was no electronics that I accidently could damage. Be very careful, when using metal tools to not shorten the battery itself.
At first I thought I'll break it too. The trick is not to pull it straight out...you need to pull ist diagonally. First get one edge out, then the other. Notice the 2 noses at the end of the cable. They prevent it from being pulled out straight.
