Just re-apply the Interface MCU firmware from the DKs downloads page: Power-up the kit with the reset button pressed, then copy the firmware onto the newly opened drive.
What Turbo J is suggesting, is to drag and drop the Interface MCU firmware file, downloadable here, into the drive that opens when you power up the DK as described to enter the bootloader in the nRF52DK user guide in order to get the standard firmware back onto the debugger MCU.
Power light is off and the port is not recognized.Whether the file of the chip is lost
