As the following people said, "Place near hot source". I agree! My phone is kind of broken so it isn't the best and I left to to charge. The battery got drained and this had happened before. I placed my phone under my laptop, since it heats up. Anyways, in order to heat up my laptop I would do something entertaining to lose focus. I continued doing what I was doing and after a while it heated up. Then my phone turned on! Definitely recommend.