Possible Reason: Pressure inside the cooker  Solution: Release pressure according to recipe; open lid after cooker has depressurized and float valve has dropped down   Possible Reason: Float valve stuck at the popped-up position due to food debris or residue  Solution A): Ensure steam is completely released by QR method, then press float valve gently with a long utensil  Solution B): Open lid cautiously and thoroughly clean float valve, surrounding area, and lid before next use