I would look carefully in the circuitry that keys the radio - possibly a diode is backwards, or a short circuit. I don't know if you wired up the GPS connection -- but it is a problem when you plug in a GPS in the CW mode, or have a short circuit there. Most likely it is something simple. I suggest seeing what component you can remove to disable the transmitter while you troubleshoot - perhaps the choke feeding the PA. Not unusual to have a small issue in assembly - do evaluate the keying circuitry. If you need more help, do query the list here.