Trying to fix my NES

[Kriven]

There's a pin on one of the chips--you'll have to go find a better tutorial--that was designed to prevent illicit carts from bing played. If you disconnect that pin (again, find a tutorial that isn't a year separated from this process) there's a chance it might work.You might also have to replace the connectors as they can get quite bent out of shape and damaged. It's probably a better idea to buy a RetroDuo Twin or some equivalent device if you're set on using the original carts.