CSI The Missing Pieces Mystery 750 Piece Puzzle - Dead Heat

I got it and the little light didn't work. The screws were too small for me to get out to try to replace the battery. Also... I know it's called "The Missing Piece" mystery Puzzles... but was it actually supposed to be missing a piece? I had an extra of and edge piece, and missing one from the middle. All in all, I have no way to discern the answer because of no light. :( Not so happy with the product.