This part is easy actually - although you have plugged the keyboard back in correctly, you've probaby not plugged the keyboard backlight in again correctly. It is located just up and left of where the keyboard cable comes throught the topcase (here). I forgot to thread the little cable through first time I reassembled a keyboard/topcase assembly and had the same problem...
Wait, I thought F9 and F10 will always show that on the screen unless the room is dark enough for the backlit keyboard to turn on? Try it in a dark room, maybe its not dark enough to even activate the backlit keys?