Hello jbsavitz, thank you for trying to help me out.
I did what you told me to do.
I downloaded from
www.ereader-store.de update-20130427.zip
Formated not quickly my sd card fat32, copied the update to it.
Placed the sdcard in my firefly hold the back button while powering on, keeping de back button holded.
But :
Request for update detected, checking updates …..
No update found. Booting device … (system hangs)
Sadly...