If the steam light flashes, please make sure you have turned the steam knob to its end stop.

While turning the lever, you will feel it becomes stiff and seems to stop at the 8 o’clock position.
Please, mind the final position is actually at 180 degrees clockwise, so you need to turn further with increasing energy until the lever is horizontally positioned, just below the steam icon. In achieving this, a “click” should be detected warning that the switch reached its end limit.
After hitting the correct position, the “STEAM” light stops flashing and you will notice that the “SETTINGS” light starts blinking.
By clicking on the “SETTINGS” button, the chance will be given to go on and complete priming. Some hot water will flow through the steam wand and you have finished the priming process correctly.

Please check the following link to watch the How-To video showing this same procedure: