You have reminded me of a couple things that have happened to me-
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When the shield is installed, make sure the pins from the ethernet socket don’t short out on the USB socket. Made things very hot and did not work, didn’t kill anything, just got warm.
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At one point I ordered 3 ethernet shields from Amazon. One of them was DOA, fortunately, I had others to troubleshoot with and was able to quickly sort out the problem. I understand you may not have this option.
Hope this helps,
-Ian