I recently designed two boards and had them manufactured for a project I am working on. Before I soldered any components, I checked the continuity of some of my connections and discovered that there is a short somewhere between my 12V line, my 5V line, and GND. It also appears that some of the other connections are shorted as well. I ordered two of each board and there is not much consistency as to which connections are fine and which aren't. For example, on one of the 4 boards the 5V lines are not shorted to the 12V/GND but the 12V and GND are.
They few things I think might be the culprit are:
1.) Some of the traces appear to be faded. There seems to be a correlation between the traces that are faded and the connections which are shorted. However, it doesn't appear that the etching for the traces is actually broken.
2.) I used ground planes on both the top and bottom layer of my boards.
3.) I noticed that the decoupling capacitor is not wired properly, and can just be bypassed.
I would like help narrowing what might be the cause of my issue, as these are the first boards I have designed. I have included images of both of the board layouts below.