It is time to eliminate possibilities. Let's do some basic troubleshooting.
Remove the memory card and lens. If it still does not power up without the lens and memory card, then you probably have a camera problem. I do not know if that model is still serviced by Canon, or not. If it does power up, go into the menus, and reset the camera back to factory defaults. Put the Camera in P mode to reset it.
If the camera seems to work after removing the lens and memory card, you want to add the memory card and test it again.
If the camera seems to work after installing the memory card, remove it, and then test it again with just the lens installed.
If it is still working by this time, let's test it with both the memory card and lens.