Im taking it you have filled the salt chamber up to the top or nearly to the top?
If so then just run a cycle and sometimes this will clear the light as its only done by a reed switch in the salt pot which tells the control board its full and turns the light off so try that and see what happens.
If still the same then its possibley a bad connection on the reed switch on the salt pot at the bottom or the switch itself is faulty. Im not sure on this version but some you can replace others its part of the salt pot but check the wiring connections to it first and also check for broken wires in the door if you are able to do this as well.
But if you don't want to go messing with the dishwasher just try and few cycles and as the water is flushed through the salt chamber this can usually turn the light off.