Original Screen Damaged & new screen's backlight won't work

Hi. I'm working on a student's HP Stream 11 note/netbook with a non-functioning screen. He came to me with the unit which would boot with the screen half light gray and half dark gray. He said he feared the unit was crushed in his backpack. I purchased a replacement screen, which the seller has told me is 100% compatible. The new screen works (when I'm shining my iPhone flashlight at it closely, but the backlight does not function. I've tried putting the old screen back on but now find nothing when I boot the unit. I've checked the connections at both monitor and motherboard, and everything seems to be good. The external video (HDMI) is functional and the keyboard, power button, and trackpad work. I assumed there was a fault in the video cable and tried flexing it at varying points at the transition from the lid to the base, with no change in display. Any ideas? I'm thinking of buying a new cable but want to be sure before spending the money and waiting. Thanks!