Where has all my electricity gone?

Bike was running with a bit of a “battery” issue; was able to jump it. Got a new battery anyway and it started right up. Cut it off after few minutes, roll it into garage and went to check my lights and no power at all. Finally found that the connecter plug had exploded inside starter solenoid from previous owner, who knows how long ago. There were only 2 wires coming from the harness to relay, but the connector I got has 4 wires. Unsure how to pigtail connector to harness??