If your Nexus 7 not charging or showing 0% battery charge or fails to power on after the standard procedure of shutting down the table and long pressing the power button (30 seconds or longer) you may want to try the following steps. Step Two does require removing the back of the tablet, which is an easy process, but we have to state that you do this at your own risk. The following steps have been acquired from various sources on the internet so I can only accept credit for pulling them together for our future FAQ section. These steps should apply to the Nexus 2013 but the detailed back removal instructions are for the Nexus 7 2012.
1. Plug-in your powered off Nexus 7 to a wall charger. (Jump immediately to step 2.)
2. Immediately after plugging it in, press Volume Down and Power at the same time.
3. Once in the bootloader menu, use Volume Down until you see “Power Off Device.”
4. Choose that option with the Power button.
5. Once your device is off, unplug the charger and then plug it back into the device.
Step Two (Requires removing the back of the tablet)
Power off the tablet, carefully pry off the back (See below for detailed instructions Nexus 2012) and check for a loose connection with the 5 wire battery connector.
Power off the tablet, carefully pry off the back (See below for detailed instructions on removing the back of the Nexus 2012), then disconnect the battery cable carefully (it's the cable coming from the big black thing on the bottom, google to find out where), finally hold the power button for about 10-15 seconds with the battery unplugged, this creates a static reset, using all of the electricity in the device and discharging it fully. Reassemble.
1. The back cover simply pops off, BUT start at the two top corners, and work your way down the sides to the bottom, and tilt off at a 45 degree angle. Fingernails will suffice, and least likely to do damage, plus you get good tactile feedback feeling how much to tug & pull.
2. Once off, you'll see the 5-wire battery cable plain as day, nothing to move or hunt for. If you see ANY of the shiny copper between the two connectors, you have a loose cable. PUSH the battery from the left side towards the connector, just to make sure it is free-floating and not glued down. It is not a good idea to pull on the cable away from the battery, just in case they've started to glue these things down, better to push the battery & cable towards the connector.
3. The black connector should slide right in, but give it an extra tuck with your fingernail, ideally you'll feel/hear it clicking into place.
4. I leave this step to your own design, but now's the time to fix the design flaw: wedge something between the side of the case and the battery to keep it snug towards the connector, and to prevent any future sliding. A quick easy fix is a length of the straw from a juice drink box. It's flexible, just the right width, and non-conductive. But plenty of options here.
5. VERY important: when putting the cover back on, hold it at a 45 degree angle (bottom of Nexus to top) and line up the tabs at the bottom around the USB & headphone connector. This area has some tight spots, and as I learned the hard way, easy to bend the tabs the wrong way. Lower the back into place from the bottom up, all the time making sure all of the bottom tabs are in place. The sides and top don't have any significant obstructions