Everyone knows what a USB port is. But what damage can USB create? There are 4 pins in a USB port. Two of them serve to power equipment and another two are responsible for transmission of data. What happens when a power pin touches ground?
Just like in a socket in our home, when we connect plus with minus, it will short circuit and damage all the power line. There are many different types of damages on motherboards as a result of a short circuit of the USB port. From damage to all the power line and power supply to damage of the BGA chip. To repair this kind of damage, requires knowledge of how the motherboard is built and we need schematics. A very important thing is to have backroom service, which includes service equipment and parts to implement an effective repair.