End of knowledge - Need help with bricked Z1C

Hello Everyone,

i wanted to flash a newer CM Rom (12.1). But since WiFi didn't work i wanted to go back. Now it seems i "overflashed" my phone... Long story short, the following is what i can do atm:

-get into Fastboot mode
-get into Flash mode

What i tried:
Using flashtool and flashing different ftf's to no success. Flashtool aborts the flash process at this line: x10flash.java:770 error (beforehand it says "parsing boot delivery" followed by "ending flash session")
Using fastboot to get into a recovery. Fastboot either gives "command not allowed" or "too many links"
At one point i was able to boot into a recovery, but that stopped working as well now.

I've never experienced a brick that crazy. Besides entering the two modes, i can do exactly nothing with it.
I have somewhat experience with flashing (owned a galaxy s3 before, flashed many times) and have flashed to the z1c many times.
No backup ofc, doh. But it doesn't matter since i backuped all my personal stuff anyway.

My question: is there any way i could do a FULL clean installation? Stock ROM or whatever. Just so i can get into a recovery at least again!