For the procedure here are the followings steps.

1. Remove the deodorizing filter
2. Unscrew 2 screws located in the back of the bidet.
3. Flip the bidet upside down and located the screw on the shroud around nozzle area and remove the small screw.
4. Use a flat head screw driver to pry open the top casing assembly that holds the seat, lid, side controls.
5. Follow the wires that are connected to the top case and remove the connectors with a firm grip pressing on the connector release clip. All the connectors are colour coded and differently sized. Thus there are no possibilities of plugging the connectors wrong way.
6. Remove the gut assembly, and bring the new gut to repairing area.
7. Reverse the step 5 and plug in the connectors to the right areas.
8. Carefully, lift the top case and place it in the gut assembly. Be gentle and care for the wires. This is to prevent wires to be torn as it may get stuck around some areas. Nozzle flap can fall at this time, you can clip it back in at the top side of the nozzle indentation.
9. Firmly grip the front with the top and bottom pressing on each other to clasp the gut and the top case.
10. Tighten the rear screws that were removed from the step 2. Do not screw in the screws too tight as this may permanently damage the bidet casing.
11. Turn the bidet upside down to tighten the small screw that came off from the bottom.
12. Insert the deodorizing filter.