The symbol you're describing is saying the salt tank is empty. Normally on this model if the dispenser isn't opening it's because it's not heating, the dispenser is triggered when it reaches a set temperature
Door lock is jammed on , take front panel and console panel off , with a screwdriver, flick door lock mechanism to open, spray with wdr0 and it should work
Are there any error codes? Check that the drain line to the sink is not clogged. Check the air gap at the back of the sink. Pull up the chrome cap and unscrew the plastic cap underneath and make sure there's no blocage there. Undo a wire coat-hanger and run it down the hose to the sink / garbage disposal to unclog any stoppages. .
