2182,
Nothing else will work if you a red flow light.. Period...
When the system checks for the salt level it will flash the red and green salt lights.. Without any flow, it cannot test the salt level.
Do you actually have water flow?
Can you feel a good strong flow out of your pool returns?
Do you have a VS pump? If so, at what speed is it running?
If this is a new pool, did it ever work right?
The cell could be installed backwards or the flow switch could be installed backwards..
Show us a couple of pics of your equipment pad, so we can see how things are plumbed..
Thanks,
Jim R.