Hello, I got the same problem as yours. Here's what i did to fix it.
1. Unplug Apple TV device from outlet.
2. Unplug HDMI cable from TV.
3. Connect Apple TV device to iMac/other mac notebook using micro USB cable.
4. Plug-in Apple TV device to outlet.
5. Open iTunes, wait until Apple TV device is detected.
6. Choose "restore" the Apple TV device software.
7. Wait until the software finished download and automatically installed the software into the Apple TV device.
8. Follow the instruction given by iTunes. (Unplug Apple TV device from outlet and Mac's usb port)
9. Connect Apple TV device back to TV with HDMI cable, then plug it in to socket.
Done
I hope it can help you guys.
I'm sorry for my bad english, it is not my mother tongue.