In this guide, I will disassemble an Asus K42J.
Make sure the laptop is turned off before taking it apart.
Here are some helpful tools：
Two cross screwdrivers and a straight screwdriver, silica gel, ethyl alcohol and so on.
Remove the three main parts on the bottom cover:
Memory slot cover.
Hard drive cover.
Optical drive cover.
Remove all the screws on the bottom cover.
Open the memory slot cover.
Remove the hard drive.
Unload the optical drive.
Then disassemble the keyboard.
Pry the four parts with a straight screwdriver.
Unplug the keyboard cable carefully. And so does the touchpad cable.
Turn the laptop over. Undo all the screws.
Screws marked with blue circle need to be removed with a smaller screwdriver.
Then turn it to the front. Remove every screws on the cover.
You must be very careful with the cover.
Pry the part marked with red outline gently. Then uncover the board.
Remove four screws securing the motherboard.
Unplug the speaker cable.
Then hold the motherboard and carefully draw it out towards the right.
Unscrew those screws and remove the heat dissipating modules.
This is what “cools” the laptop.
It really needs some cleaning.
Smear some silica gel.
Finally we can reassemble the laptop.