bootloop N910F at optimizing apps

Hello guys, im very new in here posting, ive been always a spectator..

i dont know if im breaking a rule but ive asked for help and no one helps me..

i ve an unbranded N910F live unit demo, and ive flashed all the 5.1.1 official roms out there and i always get a bootloop... and i really want to install it on my phone to fix the issues of sync and crashes when using facebook etc..

if this thread breaks a rule, please move it or close it please

any help would be great