But if there are 3 different firmware versions on market, there should be any method to switch it. Or maybe different firmware means different hardware too, so switching is not possible?
Canon often release various firmware version of a camera, the case could be small differences in the hardware, cosmetic fixes like typos in menu/OSD entries, different manufacturing facilities / assembly lines etc.
The only way to change the fw is to flash it with an official Canon firmware update, either with a fw file released by Canon, or by the Canon service personal.
