essential being the operative word.. in order to succesfully program a new or used main board it is essential that the data from the old board is downloaded complete with the parameters of the shutter and ccd image sensor pertaining to the body, complete with shutter actuations which reflect the actual use the body hardware has been put to, so these can be written onto the replacement board.
All these are possible only with the SPT program pertaining to your canon model.
Also any difficulties and Charles is only too willing to reply to your concerns with possible solutions.
The program also lists error codes produced by the body with an indication where the problem actually is instead of trying to guess.
The advanced pro upgrades offer further tweaking as listed on the website.
I need the canon 6D software for my next job!