Major issues on Micromax YUREKA after updating to Lollipop

I am having multiple issues on my Micromax Yureka after upgrading to Lollipop: 1. I am unable to pick up calls & the display is not coming on 2. USB storage connection is not functioning & won't connect to the computer 3. Unable to stop the mobile data when it's already connected, when I click the data option, it's going the open the data usage details only. 4. Rear camera flash not properly functioning, it's not timely flashing. How can I fix the issues?