Default Nexus 10 shuts off after a day of non use

I will use it in the evening and then won't touch it for a day. Then I go to pick it up and its off. I can turn it back on by pressing the power button a dozen times, it never boots up after I press it once, the thing vibrates but won't turn on. Its not the battery, because it'll turn on and still have charge.

Its getting really frustrating because I don't know what's going on. I'm stock on 4.4.2 not rooted, but unlocked. Any new apps I installed, have been removed. How can I figure out what my issue is.

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