I get a dozen or so of HDD's a week that are "dead". about half of them I can get running again by taking the PCB off, then cleaning the contacts on the underside of the PCB and the corresponding contacts on the HDD. They are very tiny, and very fragile. There will be two sets. one set coming directly from the center of the HDD where the motor is, and the other set will be two rows close together. Use a pencil eraser to clean the contacts. don't over do it. you can easily break them or rub right through the traces. you will need a safety bit set to take the PCB off. if you plan of working on computers, or any electronics for that matter, you should invest in a safety bit set from amazon. Take your time while taking the PCB off and you will see where they are. But like others have said. Once you opened it you killed any chance of getting it going again. You are not the first one to do it. don't feel bad. It's how we learn shit. before you trash the HDD grab the magnets out of it. They are crazy strong and besides being fun to play with they can be very useful.