Before you factory reset, try wiping the system cache partition, which you can do from the Recovery Menu. The cache partition has a lot of temporary system data and log files that could potentially muck things up after a system update, and clearing the cache partition will not erase any important data. Steps as follows:
1. Power down your Nexus 7.
2. When it's off, press
at the same time the power button, and BOTH the vol up and vol down buttons. Keep them down until the device powers up.
3. At the next screen, use the vol buttons to select "Recovery mode," then press the power button.
4. When you see the Android lying on its back with the red exclamation point, press the power button and vol up button at the same time. When you release them, you should see the Recovery Menu.
5. Use the vol buttons again to scroll up or down, select "Wipe cache partition," and press the power button to execute.
6. When it's done wiping the cache, scroll up to "Reboot system now," and press the power button.
The steps are illustrated in this article, but they omitted step 4 for some reason:
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