the screen has two circuits of heating element.
Left side and right side.
the electrical supply is also with separate connectors (and is naturally fused separately also).

if a complete side is not defrosting.. check fuse,... then check connector (behind scuttle grille)

for strips of heating elements not working... new screen needed

connections are inside on these.

Remove the A pillar trim. (torx T25? required)

Then you will see 2 black ribbons