My iPone 6s blacked out overnight while plugged into my mac and it won't turn on today. Even reset doesn't work

My iPhone 6s is roughly 3 months old. It was connected to my mac last night to charge when it still had around 20% power left, but it wouldn't turn on this morning. I thought it was drained of power somehow, so I plugged in through the all using the plug that came with the phone. I waited for a whole hour, but it still wouldn't turn on. I tried reset, restart, but it still won't turn on. I need my phone to work soon. Please help!!!! What can I do to make it work again?