I don't really understand what you are saying. What did you do? Were you on 4.2 and flashed the mk2 modem or bootloader? Can you state your android version and baseband? If you only flashed the mk2 modem then you can revert by flashing the mdl modem. If you flashed the mk2 bootloader and modem then you can't go back to MDL and have tripped Knox. You can get your sound and everything back by flashing the official mk2 firmware. I need more info so I can help.
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