I've had the exact same problem with the C902 as you have, it was very annoying and frustrating since the phone wasn't mine. I've included the MAIN, FS and CDA (custom pack), everything worked great, the phone was unlocked and it seemed to function properly except there was no sound, camera or music player. I've spent around 2 hours trying to re-flash the phone and figuring out what was wrong, then an idea came to my head and I've flashed the phone once again with an older version of the MAIN & FS file and I've used a different custom pack which fixed the problem and once again the phone was fully functional. So I guess the firmware or CDA your trying to install isn't fully compatible with each other and the phone itself. So now you got to go download a different firmware and CDA a try flashing your phone again, anyway good luck and I hope you will fix your phone.