Take the heatsink-fan block you have prepared with two hands. Tilt it a bit and firstly insert the fan under the metal plate labeled as green.

Once you have placed the fan as it is shown in the first picture, carefully lay the heatsink down by simply accompanying its tilting movement. Correct its trajectory in order to center the screws and the holes if it is necessary.

Fasten the 8 screws of the heatsink using a PH #00. Start from the screw labeled as red and then follow the numerical order which is impressed on the heatsink.

Do not overwork these and all of the other screws when reassembling. Do not apply heavy pressure with your hand. Simply turn the screw until you run against the stop.

Using a PH #00 mount the two short screws (M2.5×4.5) of the fan.

Using a PH #00 mount the last screw (M2.5×6.5) that secure the fan to the top cover. This is the longer one.

Reinstall the fan cable. Hold it with your finger near the end and push it straight into the connector. If you don't manage to do it with your fingers, use the tweezers.

Reinstall the tape labeled as light blue in the third picture. Add electrical tape to the edge in common between the heatsink and the fan if the thin black stripe which was there is not sticky anymore as it was in my case.