iPhone 7 died and won't restart - shows charging dead battery screen

My iPhone won't turn back on. It died and I plugged it back in, but it shows a dead battery (no chord, I get that when I unplug). I have tried multiple chargers and ones I know work, so it must be a problem with the phone? It's been plugged into the wall for an hour now. If I press the power button, it shows the battery again. I've tried resetting it by pressing the power button and down volume, but it just shows the battery again. Please help!