If a working hard drive will not work, it seems like it is a problem with the motherboard. Perhaps the area of the motherboard with the SATA controllers on it or one of the pathways was damaged due to heat.
These laptops have a known issue with the video chips..they overheat. There is a class action lawsuit against nvidia for it..google it. The mobo is no good..even if you replace the mobo, the issue will come back.