I also have the same issue. LG service center guys told me to replace the mother board. They said it will cost 8.5K INR. Not sure what to do.. Update: Guys, I took back my nexus from the LG service center as they asked me to pay 8.5k to replace the motherboard. I was clueless what to do next? Just read this article - http://www.reddit.com/r/Nexus5/comments/... Trust me, it worked. I just banged my phone by the right side on a table and the issue with power button fixed. I see my mobile now switched on. Thanks god, i did not waste my money! Please try it once before taking to service center. Remember, please dont hit so hard. share your joy if it works Murali