It probably will need to go to Canon... But before you do that be sure you have tried a complete reboot.
You removed the main and memory battery (the little silver one), and let it sit for a while. But how long? It takes half an hour to 45 minutes for any residual voltage to completely drain from the camera. You can speed up the process simply by pressing the shutter release button once, while all the batteries are out of the camera. And you can check that you got a full reboot... you should need to reset the date and time (assuming the camera comes back to life).
I agree to check all the battery contacts are clean. The memory battery in particular is only a few volts and even fingerprints can interrupt voltage, so wipe it well with a clean cloth before inserting it. Inspect the contacts inside the battery compartment, too. A contact that's bent, or any corrosion, or even a bit of anything stuck to or laying on the contact can interrupt the power supply.
Do that with the main battery(ies) too. And if you have a grip, check the contacts between the grip and camera are clean and the grip is tight (a common minor issue on 20D and 30D... I haven't seen on 50D or 7D... yet.)
That's about all you can do yourself. If none of it works, send the camera in to Canon. It might be a faulty switch or something. They'll sort it out for you, hopefully still under warranty.