Dear mon2
Thank you for your reply.

I am currently studying surface mount components, and I understand that a high side MOSFET is a component like the one in the image. I tried measuring the resistance values ​​of the three terminals of a MOSFET at multiple locations. However resistance values ​​varied greatly, and sometimes no value was obtained...
Looks like I'll have to actually look at the circuit diagram.
This time I purchased the machine as a teaching material, so even if the worst case scenario requires a CPU replacement, I may still carry it out