After installing the Lollipop system update of my Nexus 7, why does my phone keep loading?

[AC Question]

after installing the lollipop system update of my nexus 7

after installing such it keeps on loading too long and keeps on shutting down instantly then hanging up..heeelp..need to get back to my old version in my nexus 7

 

[B. Diddy]

Re: after installing the lollipop system update of my nexus 7

Welcome to Android Central! What is loading for too long? Do you mean it gets stuck on the boot screen, then shuts down?