This for someone who is experience similar issues:
Switch Powers up. Normal charge and readings. Nothing on screen.
Tools hours of measuring diode reading and cannot figured what Wrong.
I started connecting one thing at a time and power unit unit every time I connected something. Boots normal and video on screen
Finally found out I have a 1 bad or shorted speaker. And 1 bad joy con rail connector.
Each problem causes it to have a black screen. Connect everything else and system running normal.
This just for people experiencing normal charge no shorts with black screen.
Hope this helps someone