Make a decision
Flame sensor cleaning versus diagnostic
One scope
Cleaning may remove a deposit on the sensor rod.
The other scope
Diagnosis verifies fault sequence, sensor signal and possible circuit or grounding issues.
A concrete example
A one-time fouling may respond to service. The same lockout returning days later calls for a circuit and ignition-sequence evaluation instead of repeat polishing.
Which question settles it?
Repeated resets or repeat fouling deserve documented testing, not another promised quick wipe.