Use a magnifying glass to look at each square inch of the motherboard from front to back to identify a blown or fried capacitor/VRM or SMD. Use a multimeter to probe each power delivery, input and output on the motherboard to see if there are any gaps in power inlet and outlets.
Copious amount of light/lamp
soldering station if you want to solder components or remove damaged ones
Components(i.e, capacitors) to be replaced with.
You sure you can't take the laptop to a certified technician?