Computer won't boot up

[super high rank]

Ok so long story short my computer was left open but off while I was at work for nine hours. The computer was working fine other then some unrelated wifi issues I was working on before work, but when I got home the computer won't boot up. It will start and go to the american megatrends screen where it always takes me because another unrelated issue, but I also noticed a over clocking error in the AM screen that I had never noticed before but I could have just missed it. After I pass that screen and start up windows 10, It loads the windows symbol and has the loading circle which moves for a second ( which is normally all it takes to load ) but then it freezes. I guess I'm wondering if anyone has experienced this problem before. Or what could be wrong with the computer? My first guesses are GPU or PS. The entire computer is under a year old but since the casing was open and my family has animals I think they might have taken the opportunity to take a look inside. What do you think it could be and how can I test the potential problems? I should be checking this site regularly for any ideas, thanks for the help.