problem with korg ax1500g and i would like to fix it myself

[crazymarvel]

my korg ax1500g got a problem with the input i think. it doesnt take any input from the guitar and when i switch to the tuner, it shows G when i plug a cable in. even before connecting the guitar. and doesnt respond to any input. I would like to fix this myself. any ideas.??

[jacobyjd]

Maybe open it up and take a look at the input jack?