No, the burning house unlikely cause the problem. The A470 is particularly subject to something called a "stuck shutter".
A stuck shutter is another common failure mode for digital cameras. The symptoms of a stuck or "sticky" shutter are very similar to CCD image sensor failure. The camera may take black pictures (for shutter stuck closed), or the pictures may be very bright and overexposed, sometimes with lines, especially when taken outdoors (for shutter stuck open).
To confirm a stuck shutter, put the camera in any mode other than "Auto", and turn the flash OFF (you don't want to blind yourself for the next step). Next look down the lens and take a picture. You should see a tiny flicker in the center of the lens as the shutter opens and closes. If no movement is seen, then you likely have a stuck shutter. If so,
please see this link for further info and a simple fix that may help. Now recommend proceeding directly to Fix 5A listed in the article. If that doesn't help, your camera may have a more serious problem of a broken ribbon cable to the shutter. This seems to be very common for the A4XX series cameras from Canon.
Here's some info on the problem.
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