Ah - good thinking. I should have thought of that.
You might try swapping the CPU as well.
If that doesn't work, let's try pictures again. The last batch didn't have enough detail to see the solder connections. Try for some closer shots, and try to reduce the light flares on the solder joints. I don't know - maybe there's a short or a cold joint on there someplace. There's a *lot* of soldering on that board. In fact, when I was comparing mine with your photos, I discovered that I forgot to solder one of the battery clips.
It was only working because of the spring tension of the clip itself.