quote, "I swear I have never put anything in that box that I am aware of."

The "being aware of" thing is what gets one.
You won't believe how many times I clicked on things or activated lines that I was not aware of.

When the mouse pointer activated a box by mistake it's done.
Obviously there was a pic link code added in the "don't do this!" box, there is no way a dark force from outside added this.

So, nothing happened and no harm done.
You're not blocked, you didn't make anything wrong, you just locked yourself out by mistake.