You need the service manuals; they've been posted here from time to time - do an XDA search (or a Google search with XDA appended to your search terms), or a Google search should find them easily enough on other sites.
You could also take it to any local mobile repair shop, it doesn't have to be a Samsung service centre who does the repair.
If it's important enough to cause you grief if it's lost, back it up. No excuses
Trolling for thanks is lame
Does Samsung's auto-brightness implementation crap drive you to self-harm ? A solution !
Failure to search is the leading cause of male impotence on XDA
If you don't know how to recover if things go wrong, what are you doing flashing custom roms ?