Could be the battery, especially if you have used it a lot.
General information on the two types of “Resets “ - Hard Reset and Factory Reset and what’s the difference?
== What to do before you reset the Nexus 7 (2013) ==
Backup, backup, backup: if it’s important to you, make sure you’ve got a backup copy somewhere safe before you reset your Nexus 7 (2013). Also make sure you’ve got a note of any crucial app passwords, because post-reset you’ll need to set them up again. Also, make sure you’ve synced with your Google account so that all the online data Google has for your tablet is up to date. That’ll make restoring your Nexus much simpler.
== Hard reset and factory reset. What’s the difference? ==
There are two ways to reset your Nexus 7 (2013). The first option is a Factory Reset, and the second is a Hard Reset. So what’s the difference? A Factory Reset erases all of the data from your device, and while any data stored in your Google Account will be restored, all of your additional apps and their data will be removed. A Factory Reset shouldn’t touch any data stored on the internal SD Card, but a Hard Reset will wipe that too. Factory Reset is called from the Settings menu, while a Hard Reset is carried out in Recovery Mode.
== How to reset the Nexus 7 (2013) using the Settings menu (factory reset) ==
Once you’ve checked your backup, you can reset your Nexus 7 (2013) via the Settings menu. To do that:
* Open Settings
* Under Personal, tap on Backup & Reset
* Under Personal Data, tap on Factory Data Reset
* Tap on Reset Tablet
* Enter your PIN, pattern or password if prompted
* Tap Delete Everything
* Reboot your Nexus
== How to reset the Nexus 7 (2013) in Recovery Mode (hard reset) ==
There are a few key issues to bear in mind before you do this. If you’ve reset your Google account password, you can’t do a factory reset for 72 hours after the change. And on Android 5.1 onwards, there’s a security setting that means you can’t re-activate a reset Nexus 7 without providing your Google username and password immediately after the device resets. Here’s how reset the device, straight from the Google mouth:
* Turn off the Nexus
* Press and '''hold Volume Down''' and then press and '''hold Power''' until the tablet turns on. You should see the word “'''Start'''”
* Press Volume Down twice to highlight '''Recovery Mode'''. Press Power to confirm your selection
* '''Hold''' down the '''Power''' button and '''tap Volume Up'''.
* '''Press Volume Down twice''' to highlight '''Wipe Data / Factory Reset''' and press '''Power''' to confirm
* '''Press Volume Down''' '''7’s''' to highlight Yes - Erase All User Data. Once again, press '''Power''' to confirm
* After the reset is finished, reboot your device.
If your Nexus appears to '''lock up''' during any of these steps, you can restart it by pressing and holding Power for a few seconds.