Why Won't my Nexus 7 (2012) Boot?

[AC Question]

One day I was using my tablet then I went to the bathroom or something and when I came back my Nexus wouldn't turn on, I figured it was out of batteries and let it charge overnight; when I woke up it wouldn't turn on which I found strange, I have looked on other forums for solutions but none of them work. I can't even get into Recovery Mode to reset it. Is this a problem with the battery or is there something else I'm missing. This Nexus is four years old so I can't take it back to Google or ASUS. What do I do? Thanks.