Okay got it back today and all is working so far from my brief testing.
They changed the main board, power and connector to the SD slot? I've never used the SD slot, this is my interpretation of the parts listed as changed.
30 day warranty on parts and labour for repairs
I suspect this isn't an isolated case and this is a manufacturing defect on perhaps batches of these boards?
I'm really hesitant to add another 1Dx because of this, i'll see what this new 7D2 is all about and then decide to add or switch over to Nikon Pro spec'd bodies.
This wouldn't have bothered me if i had maybe like 60,000+ actuations on it but under 100 on both and one failure!!!!
...but for now i'm just happy it's working again.