I tried the diagnostic button and killed the power as described above, but no luck. The unit was installed Oct 04 so it is still under some warranty. I'll try Goldline tech support and also the pool builder to see what they say about how to deal with it.

Side question - does anyone know what the different readings are on the unit? When it was working, I knew which was the mineral reading and which was temp, but didn't know the rest of them.

Thanks