im back home and unhappy....
i was able to come to the "process of installing" of wazapp....the battery was at ~15%.....after 10 minutes my n9 still was installing it...and than it turned off.
i thought that the battery is just empty but now it seems like my n9 cant boot up anymore...all i cann see is the nokia logo on the screen.
and now??
(thank you so much for your help)