The most direct way to cover all of the possible reasons that the display is showing this way is to perform a hard reset using the following instructions.
Remove the main batteries, the memory card and the Time/Date battery (shown below). Press the power switch once and allow the camera to sit idle for 20 minutes. Press the power switch once again, insert the Time/Date battery and main battery, and the memory card and power the camera up. You will need to reset the time and date and any other custom settings. Instructions are at the following link
If the reset does not restore the shooting view, then. unfortunately, the symptoms indicate that there is a problem with the ccd (the light sensitive chip that produces the image)or the connection to it, Sensor replacement is really the only option and while your camera was not on the list of cameras Canon's on free repair program, the information at the links below does fully explain the problem and tells how Canon handled it. Since more and more newer models have the identical problem the info may give you some leverage with Canon even though, they have basically stopped acknowledging the issue publicly. You are now the 3rd person in a three month period, with an Canon camera that I have advised of this problem. Click on or copy and paste the link into your browser
Please keep in mind that my diagnosis & solutions provided are directly dependent on the accuracy of your description of the problem. As with any "do it yourself" fixes, success is a "team effort", since I can't see or touch the camera, and relies on the customer's manual dexterity and ability to follow the instructions well.
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