Bottom screen backlight and touch work, but no display.

Hi All,

I’ve been unable to diagnose this: the bottom screen of my phat Nintendo DS is blank (with maybe the faintest outlines of the display, in a bluish-green). The backlight still works, as does the touch panel. The large LCD ribbon, which I assume outputs the display, seems to be connected properly, and the socket looks fine.

I’ve tried swapping the screen with a new one, and made sure the ribbon was connected properly, to no avail. Any ideas?