I tapped the back button on my phone and the choose faction dialog was closed. How can I open it again to pick? 
Hello RammsteinAM,
I moved your post over to its own thread in the Tech Support forum for visibility in case anyone else runs into this.
We’re aware of a situation where it’s possible to skip past this choice with no way currently of getting back to it.
We’re working on a fix already, though depending on what’s needed to address it, could take some time to implement.
Thanks for the answer. I also opened a ticked in the support. Maybe it wasn’t needed since it’s a global issue but anyway I’ll wait for a response and hope I can play Vanndar soon. 