I installed a all new system using a Hayward t-15 cell. I noticed today the the 'check cell" light is on. Chemistry is all okay and pool is clear as a bell. Any ideas before I dis-assemble the system to return it to store?

Did you unplug the cord and plug it back in?

If the inspect cell LED is flashing then there is no need to return the cell.

The inspect cell light is only a service reminder.
It is kind of like the oil change light on your car.

Take a look inside the cell and look for calcium scaling.
If you see scale, clean the cell per the manufacturers recommendations.
If you don't see any scale, then put it all back together.
To reset the inspect cell LED simply press and hold the black diagnostics button that is beside the LCD screen.
The inspect cell LED should turn off.

If the inspect cell is illuminated steady then the cell is no longer producing chlorine.

PSG