smev CU322 Manuel D'instructions page 5

If polarity is incorrect electronic igniter will not function.
ALWAYS DISCONNECT THE ELECTRIC SUppLY bEFORE ANY TYpE OF
INTERVENTION ON THE UNIT
LAbEL ALL WIRES pRIOR TO DISCONNECTION WHEN SERVICING CONTROLS.
WIRING ERRORS CAN CAUSE IMpROpER AND HAZARDOUS OpERATION.
VERIFY pROpER AND EFFICIENT OpERATION AFTER SERVICING
FIXING
The appliance must be secured by means of the fastening screws (FIG. 2 - PAG. 26):
1) insert the appliance in the unit;
2) tighten the screws.