Diagnosis
The auto-off safety feature is activating prematurely. The tilt sensor is overly sensitive or faulty.
How to Fix It
Ensure the iron is resting perfectly flat and level when not in hand. Even a slight angle on a slanted surface can trigger it.
If That Didn't Work
The mercury switch tilt sensor inside the handle is stuck or defective. Unit must be disassembled to replace it.
Heads Up
Do not disable the auto-off. It's a critical fire prevention device for if you forget and leave it on.