That's odd (that the average display is gone)

However, your unit thinks the salt is 2500 ppm - when you're at push 5 (salinity) push the from 'auto' to 'super' and back to 'auto' and you should get ppm

The 2500 is why your check salt light is flashing. The inspect cell light will flash ~ every 3 months - check the cell for debris or scale and then push and hold the diagnostic button for ~ 5 seconds and it will turn off.

If you have your owner's manual, the info on button pushes is on page 14 (IIRC) - #6 identifies the unit, #7 is the software revision # and I forget what #8 is

You need to get the salt up a little to satisfy the unit - another 100 ppm will stop the check salt light.

I wish you well with this! Please keep us updated.