well, if the phone won't turn on, then you really cannot do anything with it.
however, it very well could be a battery issue. here what I would suggest:
make sure the battery is in the phone properly and plug the phone into a wall outlet (not a computer). let it charge for at least 2 hours. you should eventually see the battery pop up on the screen. after about 2 hours, it might automatically turn on and boot up. if not, then try turning it on. if you get a little anxious and want to try to turn it on before the 2 hours is up, that will be fine, nothing will explode or break (just leave it plugged in though)
if that fails, then try taking the battery out and plugging the phone in the wall and then turning it on (after waiting a few minutes).
if that fails, then when you get your new phone, charge that battery all the way up and then place that battery in your old charge. if the phone then boots up, the issue was with the charging port and not the battery.
once you get your old charge back up, then you can do a factory rest.
hope this helps.
Thank you! I'll leave it plugged in until I get back from work and see what happens. I'll end up going to the store later today anyway, I think, just to see if they have any ideas. Fingers crossed that something works!
on the edge of my seat.... j/k