Tools your need, flat head screwdriver. Phillips screwdriver just for the heatsink on CPU/GPU.
Unplug everything and then press the power button twice. Obviously it will not power on, this is to just remove stored power in the capacitors for safety.
You'll need to have the screen side laying down.
Make sure to put the screen side on a clear soft surface to not damage the touch screen.
Remove the nine screws labeled "CB" for the fans cover, with a flat head screwdriver. These are the 8 shown circled, plus 1 more in the central black area.
After the CB screws are removed, lift up the fans cover. It will be tethered by connecting wires to the motherboard. Some repairs can be done without untethering, just shifting the cover.
To remove the metal panel entirely (assumed below), you will have to unplug 2+ connectors from the motherboard. (More if you have a model with active external connectors like CATV, etc.) An alternative may be to detach the external-connector plate from the fans cover with the 3 screws label "IO-C", leaving just that small plate tethered.
I don't have a picture of this fans cover. Just be aware it is the biggest metal panel removed.
When remove the CPU heatsink it's best to heat up the heatsink with a blow dryer so the thermal paste heats up. This way you don't rip the CPU out of the motherboard socket.
Remove the CPU heatsink screws.
Make sure you do the normal CPU unscrew method. For example, start with the upper left, unscrew just a bit, then go to the lower right and unscrew just a bit. Next jump to the lower left, unscrew just a bit, then next the upper right. Continue this until you can remove it.
If the heatsink doesn't easily left up, heat it up more with a blow dryer. To make sure you don't rip out the CPU. Ripping out the CPU from the motherboards socket could damage the CPU and the motherboard.