Many users have desoldered faulty capacitors (usually bulging or leaking caps)
Or resoldered connections (usually around the power connector)
Obviously it depends on the fault that it was having originally, but generally it is advised to:
View the Motherboard (discolorization or broken connections)
Clean the motherboard (usually circuit board cleaner, and high compressed air)
Reconnect any onboard connections (even jumpers)
But all up, usually once the motherboard is found faulty, it's faulty