Hello,
1) Please check debugger cable and cable polarity (seems to be correct, but just to make sure).
2) Does the debugger have JP10 jumper which provides power supply? If yes, please disconnect this jumper.
3) Could you please the debugger with different board or this board with different debugger?
4) Have you ever been able to connect to the board? If yes, what did you load to memory?
Regards,
Martin