Keep in mind I'm not there physically, so I can only advise and not give your definite answers. I doubt that you would have three problems (hard drive, RAM and video) all at the same time. However, it is possible. I suspect you need a new motherboard There could be hardware errors from the MB that make the HDD and RAM appear to be defective.. Your laptop is rather old, so it might be time for a new one if you can afford it. You can start replacing parts on the old machine but might end up spending more than a new machine will cost. Sorry. One last thing you try is letting the laptop cool at room temp for a few hours then put it in the refrigerator for 20 minutes. Try the diagnostic right away while it is still cold and see if anything is different.
If you know of a repair shop you trust, getting an opinion from them would be a good thing to do.