Google Nexux 4 with LolliPop version issue of hang up

I have google nexux 4 which i've bought 2nd hand. Now when the KitKat is updated to Lollipop it is creating an issue. nearly every 24 hours it got hanged and I've to restart the set, even it is not restarted by pressing the button. I've to take off the battery then it is restarted. Any one can guide me how to fix this error

You could hard-reset the phone to see whether it rectifies the issue. (Beware that it wipes all data on the device)
Otherwise, there are many posts in Android forums on how to rectify this.
IBF hardly seems to be the forum such queries !

Factory restoring the phone or else I would suggest contacting the customer service technical team.