Diagnosing Hardware Problems

Yeah, I can't stand trying to figure out what's wrong with electronics sometimes. I have a Sega Genesis controller that for some reason refuses to work, and I have no idea what's wrong with it. I've tried cleaning the button contacts but it does nothing, so I have absolutely no idea what's wrong with it. That's not too bad compared to what else I have to look at. I had a computer that seemed to be broken. Turns out the sound card installed was preventing it from working properly. Now that everything else seems to work, neither xp or vista can format and install on the sata hard drive I have in it. Also, the 160 gig EIDE hard drive is creating the same problem the sound card was making and preventing it from running. The next step it to take an already working hard drive with an operating system and put it in this computer and see if it works, if not I will know that the computer is no longer a viable machine. Diagnosing Computer Hardware is extremely irritating and I hate it.