Motherboard
The motherboard is a very complex and fragile system. Once the motherboard craps out, it has to be replace. Though there are a few cases where soldering can repair it.
Any number of things can go wrong with the motherboard! A brief list includes: short circuiting, overheating (dust compiling or keeping the laptop on a pillow or bed surface), spilling liquids, users who try to “upgrade BIOS” but clearly don’t have a clue what they’re doing and even rusting due to a highly humidified neighborhoods (we’re looking at you Long Island!)
All you have to do to prevent your precious motherboard from crashing is to make sure it stays cool and dust free. Please invest a little money into caring for your laptop and it will serve you well.