Open the top shell to the right.

Optionally disconnect the ribbon cable to give extra working space by pulling up on the ribbon cable connector's locking piece until the ribbon cable can freely slide out.

Unscrew the 2 screws holding in the fan and pull the fan connector out. There is no locking mechanism on the fan connector.

Slide the new fan onto the mounting posts and replace the screws.

Reconnect the fan connector. Ensure the positive side (red) of the fan cable is on the left.

Reconnect the top shell ribbon cable and press down the locking tab fully before reassembling the mouse.