can a dev explain why I cant intall 4.30 cfw

I have been reading in ps3 wiki and was wanting to understand how can 3.55 ofw be installed with 3.55cfn and install with success. When I install 4.30 ofw over 4.30 cfw I get a data corrupt and it just stops installing I have been messing around with the .pup files unpacking and repacking. I used some of the dev tools to read the files. Can a dev give me a jump start on reading these files maybe i can get 4.30 cfw to install over a 4.30 ofw any information will be helpful thanks

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