Yes, that one LED was mistakenly soldered the other way around.
This 16x16x12 LED cube was supposed to be 16x16x16, render 3 LED colours, play animations, and have a playable 3D pong game.
Well, in the end it can play animations using red LEDs, so at least it's something.
This project was made with a group of college friends for a university course where you were allowed to build anything your heart desires as long as it's related to your study program.
As you can see, since it was for a course we were bound to a time limit. The reason this project was never fully realised is due to... here it comes...
Our LEDs from China were severly delayed. They even sent us the wrong ones at some point which we had to send back. Once we finally received the right LEDs we started soldering them.
It was a long and painful process.
Literally painful due to all the burn marks from soldering.