If that technician knew what he was talking about you wouldn't be posting on this forum most likely, because he would know how to fix it. If you want the technician to help you then you should follow what HE says, otherwise you're going to have to trust the advise you get.
Your display hardware is comprised of 3 basic parts...The LCD, the back light (which happen to be LEDs, in this case) and the LED power supply which is the dc-dc converter which people generically call an "inverter" because they haven't worked with newer type display hardware in laptops. Most times the converter is integrated on the LCD logic board, but on some models it's a separate piece. If the LCD, converter, or LED system go out, your computer is probably still working, it's just not able to display the image due to a failure on either of those three parts (it could also be the screen data cable also). If you plug in an external monitor and it works, then that tells you the computer is working, and the problem is in one of those three screen parts. So we've isolated the problem to the screen and we can work from there. If an external monitor doesn't work then that tells you the problem is somewhere besides the screen...and we'll know where to go from there and know with high confidence which replacement part/s you need.
