As v-2samrc asked, what is the problem requiring MB repair?
General questions you need to ask yourself:
(1) Electronic knowledge. Can you isolate a defective component? Example. You can SEE a blown cap, burnt resistor, or blown diode. Can you identify the circuit associated with that component, and determine what other (nonvisible damage) is associated with that.
(2) Test Equipment available. At a minimum a DVM
(3) What are you abilities with a soldering Iron? Need a Low wattage iron and knowledge of working on a multilayered Circuit board. A capacitor is fairly easy to replace, but a flatpack IC is difficult, almost impossible for a novice.
In general, The MB is considered a "Throw-away" item unless the repair is relatively simple by manuf. That is the time to determine what needs to be fixed and the repair time exceeds the replacement cost. If someone has say bricked their CMOS (BIOS) chip, that would be a simple repair, But they have the equipment to remove a Flatpack chip.