I’ve taken a pendant light out, 3 black wires, one was connected to the brown wire coming from the light the other was connected to the blue 3rd wire didn’t appear to be connected to anything but it may have come loose when removing the old light and I didn’t notice. I put tape around the two wires I disconnected and wrote on which was blue/ brown, connected up to new ceiling rose, light is working fine but now none of the other downstairs lights work, can someone tell me where the 3rd wire should go?