Hi, I bought a Nexus 4 phone around a year ago. I've upgraded to the latest OS (full of bugs; my photos app wouldn't even open until the most recent update). Anyways, there's a big problem with the phone - it randomly shut off two days ago, and it was around 70% battery. Pressing the power button on the right side didn't wake it up, nor did the volume up/power combo. When I tried plugging it in, the screen wouldn't turn on at all. I plugged it back in a few times and pressed the power button for a good five seconds or so, and I finally got this: But it was stuck on this image. I pressed the power/volume buttons a few times (unknown combination; I just messed around with them) and got this: The image was going back-and-forth between the above one and a full-battery icon. At this point, pressing the volume-up+power button returned the phone to normal. I thought it was just a one-time thing. Today, however, the exact same thing happened again and I had to repeat the whole above process. It's becoming a really frustrating problem. What is the cause of it?