2001 Ford Ranger Regular Cab "pure radio wont turn" Questions

...radio,etc lights just flicker on door,etc Hello Sound like a bad connection or dirty battery cable ends.You will need to clean the battery terminals. Take a wire brush or some emery cloth or even ...

...radio and all of the lights, and the engine wont turn over at all. Tried to jump the battery but that didn't work. Could this be a relay or a fuse or something bigger. Would appreciate any ideas. ...