There are two lamp driver boards, one in the front and one in the back. These provide high voltage and starting current for the lamps. Each one has a square fan mounted to a bracket.

Remove 2x T10 screws holding each fan bracket.

Two cables are held in each fan bracket's cable clips. One is for the fan, but the other one needs to be disconnected and slid out from the clips.

The fans are held in their brackets with four plastic push-rivets. These can be pushed out from the back with a screwdriver or small punch -- if you are careful, they can be reused to mount the new fans.