Can you please try the following:
First plug in your NX2LP DVK, with a working Nand Flash. Then in the utility it will identify the Nand flash.
Once that is done, please remove the working nand flash from the socket, and on the fly put your nand flash with the buggy firmware. Then do 'CTL + w" which should erase the Nand flash.
Please try and let me know.
Thanks I have tried it and it worked. Although I have some reservations on the need to change components while the system is powered up.