Root Nexus 5 stuck at optimizing app

[mssux]

Hi,

I have run into a problem for which I don't really seem to find a solution.

Phone - Nexus 5
OS - Stock OS 5.1.1.

I wanted to install Franco Kernel on the phone to improve performance and battery life. I followed the listed step but unfortunately now the phone is stuck in the "Android is starting....optimizing app" loop. It optimizes all apps and then restarts and does the same over and over again.

Steps I followed:
1. unlocked bootloader using fastboot commands - this also did a factory reset
2. signed in and updated all apps - because without this the device doesn't show up on PC
3. installed TWRP 2.8.6.1
4. used SU 2.46 to root the phone (installed it from internal storage using TWRP)
5. flashed franco kernal r71 using .img file with fastboot commands

I have also tried full wipe using twrp but it is still in the same loop.

Any solutions?

Thanks in advance!