‘No Signal’ would typically be a notification from the TV, that it isn’t getting a valid signal for video input, on the selected HDMI port on the TV.
- Try switching in TV settings between inputs, to verify that the selected HDMI port is the one that Apple TV is connected to.
- Verify the HDMI plugs, that they have a good connection in the port; not loose or anything like that.
- Else try a cold restart of the TV as well (not standby, but really off for a while — or use a software restart function in the TV settings).
If the status light on Apple TV is glowing continuously, then it has started up properly, and passed its self-test. So there seems no reason to suspect an error on that end at this time.