'06 focus fuse box replacement

Hello everyone, Dealer suggested to replace the SJB Module (Fuse Box) as it is rusted due to water leakage....total cost (more than $600)...can't afford.

I found the SJB module from a junk yard and plan to replace it by myself. Anyone knows if it is easier to do it and I won't blow up anything, and also whether my vehicle key will work with the new module or not, I only have one key? or if I'll need to visit the dealer again. They already skimmed $95 just to tell me that I've to replace SJB. ANy response is highly appreciated
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