My problem is fixed since yesterday night 
, see my post here:
If somebody needs a detailed description how flash the Fairphone with SP Flash tool, write me a private message.
Please note, that all data will be removed with this step, so make sure you have a backup.
If somebody wants to flash the phone, write me a detailed description, which steps you did and whats going wrong.
After the flashing you can install the Google Apps and restore your backups. Then you can use the Fairphone Updater and all should be like the Fairphone Team it planned.