You have no way of knowing exactly what is wrong hardware-wise (and neither do we); to do that you need to have experiencing with diagnosing electronics like that, and you clearly don't have that experience because you already would have diagnosed it if you could. But it's fairly obvious the NAND is stuffed unless you're missing or not doing something really obvious when flashing that neither you nor us have picked up (and if you've done everything in Hopper's thread, the chances of that are pretty much zero).
Take it to a local mobile repair shop, but beware...Some in some countries lately seem to be flogging people this 'I can replace the 'power IC' fix', and I don't think I've seen a single case where people say they've been offered this as a fix and it's actually worked (they haven't posted here afterwards saying so at least). If you want it fixed first time guaranteed (assuming there's nothing else wrong with hardware) without having to pay extra labour/parts for a fix that won't work, you replace the motherboard.
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 ?