Q: appletv

i just bought apple tv today, was setting up onscreen when it asked to update software, i said ok. took a long time, i left the system on unattended for an hour or more. came back and the screen was black. with no remote response. or light on the unit. i unplugged to reset, then the display was a symbol to hook to pc with a usb cable and hook to itunes. i did this but still nothing when i opened itunes to restore appple tv. can you help