I got the nexus 4 phone in August of 2013. It had been working great until a couple weeks ago. I would lose all signal, phone would go black and not able to power back up. I have changed the sim card and did nothing, I have done a reset on the phone. Has anyone else had these problems? or anyone no what could have caused this? I dont want a new phone cause I really like the nexus 4. Thanks for any advice.