That's a valid reason. I was only really suggesting trying a different power source as a test.
I could be missing something, but I can't see any glaring problems there. I'm not completely confident in the twist together wire joins, but I doubt it's the key issue.
If you do decide to order a new module, it will certainly help eliminate hardware failure as an issue.
If your module didn't come with a tag for testing, it would be good to get one at the same time, for testing. The larger "cattle ear tag" types will give you better reception for testing, compared to the, smaller implantable type. Make sure that is the ISO11784/85 FDX-B type.
