Share your experience!
There is a huge thread here about downgrading:
/t5/Software-Updates/Downgrade-Z3-compact-and-others-from-Lollipop-to-KitKat/td-p/955640/page/29
Is your phone locked to a network? Have you ticked wipe data and cache?
You should tick wipe data. Not sure about the script message, but make sure to exclude baseband.
@Nikki3 any news?
@Nikki3 So if you flash KK the phone turns on correctly? And after you update to 5.1.1, problems show up?