In my experience there are a couple of ways of getting a TSN mismatch. The obvious one, as pointed out earlier, is that the MB was swapped. The crypto chip on the new MB would obviously be different than what is printed on the box label. I did that exact thing with a couple of S1 boxes - swapped the lifetime MB into a better case. The other possibility is that what the OP is seeing in the SW is the TSN of the image from Instantcake. That would show up initially but should get corrected if he does a C&DE and then a Guided Setup. I've even seen the TSN in the SW show up as all zeros until I ran through that process.