Start by plugging the battery directly into the display and disconnecting everything. It should at least light up even with nothing else on the system. If it doesn't work, try a different cable.
Thanks. I tried this with every cable I had and in both connectors on the display but nothing appeared. Guess this points to the battery being dead (low on juice or literally just dead), or I guess the display being broken, right? I suppose I'd put my money on the former.
Start by plugging the battery directly into the display and disconnecting everything. It should at least light up even with nothing else on the system. If it doesn't work, try a different cable.