[Q] flash rom without system topic

Is it possible to flash a (stock) rom on ascend p7 if I format the system?
Backround: I want a complete fresh system.

My problems:
If I do a factory reset, I´m nor enanbled to start fastboot mode.
Also it isn't possible to connect my phone to the pc and use adb.
So I cant flash TWRP to use my nandroid.
I'm on stock-recovery to install a stock update.zip

So I didn't do anything for now, because I'm not shure that it is possible to get my system back.

Any solutions?