Wont turn on and won't stop charging

So I plugged the phone in to a charger and it gives a flashing message sayiing charging battery. It's been plugged in for a couple hours now, I tried to turn it on a few times while on the charger, nothing, just gives me the same message. so when I took it off the charger it still wouldn't turn on. How Lin is it supposed to charge before you can turn it on? And shouldn't I be able to turn it on while still on the charger? It doesn't have a SIM card in yet, not sure if this affects any of that.