No more backlighting on an ASUS FX506LH laptop

Hi, I replaced the screen of my laptop that was broken, and suddenly I have no backlight during manipulation. However, I only touched the screen and the cable. When I put back the old, broken screen, I don't get any backlight either (it was working before). The inverter is built into the screen, so it can only be a default with the cable? Or what else?
I checked with a flashlight on the back of the screen and the display works, but it's not illuminated. I've also plugged the laptop into the TV with an HDMI cable and it works. I've checked the keyboard shortcuts to disable the screen or duplicate it, etc...
I also checked the connectors on the motherboard in case one of them had become disconnected, but everything seems OK.