If its for school you may be able to apply a good enough pc onto your school loans if you cannot afford one right now. If you dont want to do that i would look at replacing the laptop with what you can, if it took several technicians to decline it, it usually not worth opening the can of worms.
If the pc was unplugged before it was shorted by the water then everything should be okay as long as the system was able to discharge all the way before any shorting. If everything looks dry then i would unplug everything from the power supply and see if plugging it into the wall alone has any problems. It should still turn on and the fan should spin. If it works okay then try plugging the motherboard in. I would disconnect gpu and see if pc works with onboard graphics if everything works then i would plug in the gpu and see if it works.
Try reseating ram. Or updating wondows