1997 Ford Explorer electrical issue?

My explorer does NOTHING when I turn the key, I replaced the starter relay, the key switch, and the ignition switch, but nothing, when I turn the key nothing, no dome lights, nothing. If I cross over the starter relay, I have power and it runs but as soon as I uncross it the engine dies and no power. Sometimes the starter stays engaged and I have to unhook the batt to get it to stop. What could be the issue? Thank you