I use ns-usbloader too and can't send the payload with that too@Raugo might be right but before you do that. Can you try this ns-usbloader first and use atmosphere payload or hekate payload ? You will need java to installed for ns-usbloader to work first. I use ns-usbloader a lot and its much better than TegraRcmGui. Surely, I use TegraRcmGui sometimes and still working fine but I use ns-usbloader a lot. Try it.
I don't know that...The solder points are really near to the usb port maybe the problem is in the board not in the usb port himself., check the wire or try with the alternative D+ D- points.