If the AVS30 fuse blows (MOV gives a momentary short and therefore takes out the fuse) due to a transient then the AVS will not work and LED’s will extinguish i.e the unit will appear dead. Replace the fuse with a new 0.5A HBC Ceramic, antisurge 20x5mm.
This fuse in addition to a spike protection is also used as the control circuit supply input fuse, not to be confused with an external load fuse.