Are you able to power on the phone without the battery, just plugged into the wall charger? Make sure you plug it into the wall.
So I just got home from work and have it plugged into the wall instead of just into my work computer. When I tried turning it on without the battery in it, I just got the big battery sign with a question mark.
I just put the battery in and it actually turned on, but it won't let me factory reset until the battery is charged to at least 25%. I guess I will just wait and hope that it charges... it has remained at 5% battery for the past five minutes or so. I'll update in an hour or so!