Upload & Sell: On
Ageofempires -- Sorry to hear about your troubles.
You must know that even new gear has a slight risk of failure, hence the warranty systems.
Used gear is exponentially more risky, as you must know. That doesn't mean you shouldn't buy used gear, just go into it with a clear head.
As an IT pro, you should be well familiar with system redundancy, and measures to safeguard operations. The first step is to have multiples of whatever gear most at risk, not relying on one server, but several (including off-site, not applicable here!). In other words, with used cameras, like used cars, my policy to own several, unless I am the kind of person that enjoys unexpected catastrophes! (And I don't!) I don't want my car breaking down, leaving me stranded with no wheels to get to a gig, and I don't want my camera going down with no back-up.
I understand you are dipping your toe into the Canon pool, and undoubtedly on a budget. But as a technical pro, you should realize you are putting yourself in a tight spot, relying on the one body. No problem doing so, just be realistic, and get over your disappointment -- easier said than done with a new toy!
I'm sure your situation will be resolved favorably. KEH is a excellent seller. In the meantime, I'd suggest you buy a new or used T2i (amazing used prices!), T3i, or the new T4i, to get a more technologically up-to-date Canon camera that can act as a primary or back-up to your 5D.
Best regards for a happy Canon ownership experience.