I just want to listen to the music, but I have to wait for more than 5 minutes until the led turns off, what can I do about it?
You could just open up the terminal and type this:
xset dpms force off
Once you press Enter to execute the command, it'll turn off your monitor instantly. This works with every X server. If you press a key or move a mouse, it goes back on (maybe you want to change a song or something). I'm using this method to listen to the music all of the time.