Exclamation [Q] Dead Z2

Hi gusy, yesterday i received my vodafone Z2, 6503, DE. I succeeded in taking an backup of that TA partitions, unlocked my bootloader and had root afterwards on firmware .323.

In Detail:

->stock D6503_17.1.2.A.0.323_Vodafone DE
->root by Easy Root Kit
->TA Backup
->unlocked bootloader
->TA Recovery
->Installed Z2-lockeddualrecovery2.7.XXX-BETA.installer.zip from here :

So far so good. Stock rom with root (checked with root checker) and able to enter the recovery using quickboot
-> copied newest CM11 nightly + gapps
-> entered TWRP Recovery
-> Factory Reset (ink wipe)
-> flashed CM11

and now... not even a SONY Logo, only vibrating. Ideas? Thanks a lot!

Edit: I was able to restore the 323 FW with the flashtool and stock image. The question is... how to get CM11 now without bricking the device