Check Cell light: what your manufacturer actually means by it
Check Cell is not one condition. On some systems it means scale on the plates, on others a short or an open circuit, and Hayward does not print that label at all. Start by confirming which box you have.
Checked 63 manufacturer manuals on file Spot an error?
If your controller is a Hayward AquaRite, it has no Check Cell light. Its cell light reads Inspect Cell, and flashing and steady mean different things. Go to the Inspect Cell page instead.
Each brand's wording appears here once two readings of its own manual agree. Check Cell is the clearest example on this site of why that matters: one brand uses the label for scale on the plates and another uses the same two words for a short circuit, and guessing between them sends someone out to buy the wrong part.
Then what
Where Check Cell means scale, cleaning is the answer and it costs almost nothing. Where it means a short or an open circuit, cleaning changes nothing at all. That is why the label alone is not a diagnosis.