Upload & Sell: On
I didn't mean to imply that you had water damage. Our problems are probably caused by "connectivity issues". In my case, corrosion is the most likely culprit. In your case, "a knock" could easily explain it.
With respect to getting a 1DX - don't sweat the small stuff. The cost to replace your 5D with another one (used, in E+ or better condition), would be about the same as the sales tax that I'll have to pay on a 1DX, later this year.