NEED HELP PLEASE !! BOOTLOOP At OPTIMIZING APPS

I just flashed 5.1.1 from Sammobile over 4.4.4 firmawre on my 910F , and now it goes to Optimizing apps and then reboots, then again optimizing apps then reboot endless loop.

Please help me guys !

Any chance i could just go back to 4.4.4 ?

Any guide on what to flash (Bootloaders / modems for 4.4.4 ?)