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Unfortunately that error indicates that the core system files are corrupted. You may need to do a factory reset to reinstall the device firmware. Before that, lets clear old system cache and see if it works or not.
First connect the Nexus to your computer and backup all your important files and documents to it.
Then follow the steps below to clear cache.
If it still not working then you have to boot into that mode again and this time select "wipe data/factory reset". Then factory reset it. After factory reset, setup your tablet again. This will reinstall the firmware and fix the problem.
Please let em know if that didn't work, so we can continue troubleshooting.
Remember, this is not my final answer. If my solutions didn't work please don't rate me bad or poor. Instead please reply back to me and I will continue to help you until we fix the problem or you are satisfied.