With the mixer off, press and hold the menu button. 

Power up the mixer and continue holding the menu button for more than 5 seconds (and less than 10 seconds.)

Release the menu button. 

Confirmation that a hard reset has been performed will be shown by the illumination of the buttons as shown on the below diagram.

If the hard reset does not resolve the problem the first time, please try this another two/three times.

If the mixer still does not power up, please check the fuse.

If the fuse is not the problem, please contact your dealer or local A&H distributor to arrange a service.