Unhappy [help] problem with android kitkat update on nexus 4

i have nexus 4 model.
It got automatic kitkat update this morning.
So i installed it.
first it took very long time to boot.
Then when it was installed i restarted the phone.
but now it is just stuck at screen with four colored circles submerging.
when i restart it , it is again back at same screen.
please help...