If all the display lights are turned on, when you disconnect and reconnect the power cord, 
try touching the first key at the top right, the lights go out and only the stand-by key remains. 
Now you can even turn on with the remote control. 
Otherwise they sometimes go out even after 8-10 minutes. 
This procedure worked for me, then I don't know if there are other causes that don't allow you to do it. 
https://www.youtube.com/watch?v=il94UMwBfRU
