iPhone 6s plus clone shut down

When I got to school yesterday, I immediately turned off my phone because I usually do it. Then by 7;30 in the morning, I turned it on but instead of the apple sign, it showed Chinese characters which I cannot read. And sound like "toooooooooooooot" started coming out from it. It stayed like that for an hour then it finally shut down. Please help, I do not know if I need to charge my phone or just let it and keep it for a while. We're quite scared because it was really hot yesterday. Thank you in advice for your answer.