If you have any browsing or editing software, try this. Open one of the camera's images in the software. Click around on the toolbar and find something that says "information" or "properties" and click it. Click and scroll around some more until you see something like "EXIF Info" and click on it and see if it lists your camera's serial number. It may or may not but it's worth a try.
The sample I'm posting shows the results found in Irfanview Image Browser. It's a FREE download if you don't already have it. Canon's image browser may also show this information.
If you have Windows, try right clicking on the image file and clicking on "Properties" and scrolling around there for the same info. I believe there are some online sites where you can also access your EXIF data.
