I installed the new android 5.1 update to my Nexus 4 today and literally within 3 hours my phone had its battery drained from 100% to 0% within 3 hours on standby. I'm wondering if I can bring my phone in to be reset or something back to my old OS?
I don't think it is possible to get it restored back to the previous update. One thing that happens to me when I update my phone is that the battery will drain dramatically, it's not even funny. I just perform a factory update, it restores to the latest versions but works out any issues that happened during the update process. You can do that by going under the privacy settings of the phone, it's really easy to do. Here are the instructions from google to do it: