DIAGNOSIS: This is a mechanical failure of the button's latching mechanism. The Cool Shot button is supposed to click and stay depressed to keep the fan running without heat.
FIX: There's no easy user fix for this. The button mechanism is part of the main switch assembly inside the handle. Attempting to disassemble the handle to repair or replace it is complex and risks damaging the unit or creating a safety hazard.
IF THAT DIDN'T WORK: If the button feels mushy or completely unresponsive, the internal switch may have failed entirely. The symptom and solution are the same—the unit needs professional service or replacement.
HEADS UP: You can still use the cool shot function by holding the button, but it's annoying. Contact Revlon support; if the dryer is under warranty, they may replace it for this defect. Don't try to glue or wedge the button in place.