1. A faulty power charger or even use of replacement AC adapter, which could have power spikes that can easily damage your computer's motherboard.
2. Overheating cased by blocked cooling system can warp the motherboard and lead to failure of board's components.
3. Electrical storm and static discharge can also be damaging for the motherboard.
4. Physical Damage, i.e. (stepping on the laptop, or dropping it)
In any situation that a motherboard failure happens, it is very time consuming to diagnose and replace individual components on the motherboard.