I have a Hayward and I just realized the same thing last week. I've been blaming the lack of chlorine in the pool on the heavy rains we'd been having, but after a week of no rain and having just shocked the pool (again), and zero chlorine (!!!)...
I looked at the panel on the salt generator and the lights were all off - cycled the CB panel, came on momentarily, etc. Still under 3-year warranty, so the guy came out and said he had to replace the circuit board. I was explaining this to some friends and they said they had the same thing (no idea what brand) and that the humidity here in FL causes them to go bad.
No idea how much it would cost, but if you're an EE you might be able to figure it out for less if you're not under warranty.