Changed Canon serial number

[Bi2L]

Hello to all,
This my first time here in this forum and I don't know where to start... hope this is the correct section.

I have sent my Canon eos 40D to service(Intersys S.A @Athens,Greece) to change my broken mirror and they sent it to my with firmware 1.0.2 (it was 1.1.1), and lot of hotpixels (about 5000++ hotpixels, before service I was having 10 hotpixels).

So because all of this changes to my camera, I check the exif data of my files, and I noticed that at the exif data before service I have serial number 1030507518 and after servive I've got serial number at the exif 0620421889.

So, how does my serial number chance from 1030507518 to 0620421889?? I Think that the change all the inside of my camera and sent to my another old camera... but how can I prove it?

Is it possible to change the serial number from exif inside the camera by programming the Cameras code? And if Yes, then why they change it?

[Phil Harvey]

The serial number is likely stored in one of the chips on the main circuit board of the camera.  If this number changed, I would guess that at least the main board was changed.  A simple firmware update shouldn't affect the serial number.

You say you sent it in to replace the mirror?  Maybe reading the service manual would give you a better idea of the work they must have done:

EOS 40D Service Manual

- Phil

[Bi2L]

Thank you Phil,
I will read the manual to get a better idea.