Nexus 5 stuck on colored balls/dots..!!!

[AC Question]

I got a small 10 mb update for my Marshmallow. I downloaded that and after it was done, while installing an error came. i switched off my phone thinking it would start properly. Then it got stuck on the colored balls/dots that come before the welcome screen. I tried switching on and off but no success.

Then I did a factory reset and after everything was done and i thought the phone would get switched on, but it again got stuck on those colored balls. Now the phone is not getting switched on..

Plesae help..!!!