I have a galaxy s4 i9500, but It was already with superSU when I bought it from eBay, and then it started to turn into Japanese and into safe mode all the time, so I wanted to flash it back to stock Rom. But I forgot to turn on USB debugging, and tried flashing stock Kitkat 4.3 via Odin (Bootloader, PDA CSC and Modem). So now my phone won't turn on after boot logo, it can't go into recovery mode (it writes "system update failed", and when i go into download mode and try flashing CMW or the stock Rom it fails. What can I do??