Default Charging screen keep looping can't complete shut off.

As all you know when charge this Samsung Epic 4G Touch at complete shut off, you will a screen with battery picture right. That's screen it keep looping on and off. It will stop looping on that screen and vibrating if I plus the USB charger cable in or remove the battery.
I can't turn the phone back on once I shut off till I plus USB charger cable in.

It's seems to me this USB or Power button problem.. Or is it could be the software problem?? Free to post if you experienced similar or have same problem with it.