Experia E3 - 2203 Lte version

Hi everyone. I tried to update it from CM11 to 12 but. My phone is not booting up. Stucking on the logo of SONY and after that black screen flashing. Tried to flash
over flashtool, but it doesnt let me , because dev. deb. mode is UNCHECKED. ( as it says ) . Tried sony companion fix, but it doesnt let me :/ CAN ANY1 HELP, please?