I built and programmed a charliecube out of common anode LEDs, and it was working great. However, I noticed that certain lights were always on recently. I did some trouble shooting and found out that while set to INPUT mode, the wire connected to A0 is acting as a cathode for the other pins set to HIGH OUTPUT, causing some lights to turn on very dimly whether I want them to or not. If it is supposed to be on, it will then go up to it's intended brightness level. While I was trying to figure out what was wrong with it, I cleaned all the scraped off the extra contacts on my perfboard and wiped the whole thing down with alcohol just in case it was a connection issue, but no luck.
I had issues that were kind of similar with the serial ports being on digital pins 0 and 1 before, but I moved those connections to other pins which solved the problem. I'm thinking I may just change the pin for this one too, but I looked up the specs for a Nano, and the A0 pin doesn't seem to be any different from the next few analog pins, which are working fine. I have a feeling I may have damaged the board from toggling it's pinmode too quickly, but people have told me that's not possible.
I have a spire of the cube breadboarded at home that I left running for 5 days straight, and it developed the same issue on a different pin, which is why I think it may be some type of degradation