I had an old sony vaio laptop with a broken screen so decided to get a new one from eBay. First, the one they sent was faulty because it had a mark on the screen, so I sent it back. But the screen did turn on and work. When I got the new one nothing showed up on the screen at all. I plugged in the original broken screen (which normally showed some lines and marks) but still nothing. When I plug in an external monitor it works fine. On both the old broken screen and the new one, not even the backlight would come on. I shined my phone light on the screen and it showed the VAIO logo and window logo when the laptop boots, but then it goes blank.
When I go into the setting to make sure the laptop screen isn't just disabled, its set to "duplicate screen".
Also, the laptop is running a clean install of Windows 10. It originally ran Windows 7. I don't know if that makes any difference.
I've tried to update drivers in the device manager too, but that hasn't worked.