Iphones been charging for 3+ hours and still isn't turning on

My iphone 6 has been having terrible battery issues lately but sadly i can't afford to replace the battery right now so i've been dealing with it. However, my phone just died three or so hours ago and still isn't turning on! This is kinda URGENT, because it's finals week for me at school and i really need my phone tomorrow to be picked up early as i have an empty block. I'm desperate! I've tried hard reset (left home and power button down for about 1 minute and still nothing happened). The Charging icon thing is showing up but it's not turning on.

Then… How the HELL do you know your CHARGER or CABLE or even the OUTLET you have it PLUGGED INTO is ANY GOOD?