The "no signal" error message can be numerous issues so it can take several different troubleshooting methods.
Plug in the computer to a wall charger and hold down the power button for 20 seconds -- does it power on now?
If it does not power on, it is more than likely a loose cable within your computer or the video card is bad. Unfortunately, either of these options will require opening up the computer which means you will need to take it to a computer repair shop unless the computer is less than 1 year old. If it is less than 1 year old, you can contact ASUS to have it replaced under warranty.