PCA10056 erase error

[mjw]

I'm using a PCA10056 (NRF52840 Preview DK) v0.9.1, and trying to erase the existing firmware, but running into issues.

I've tried nrfjprog -f NRF52 --eraseall with version 9.6.0 of the NRF Tools and version 6.16a of JLink. The log file contains:

• FUNCTION: open_dll.
• FUNCTION: open_dll.
• FUNCTION: enum_emu_snr.
• FUNCTION: enum_emu_snr.
• FUNCTION: enum_emu_snr.
• FUNCTION: enum_emu_snr.
• FUNCTION: connect_to_emu_with_snr.
• FUNCTION: connect_to_emu_with_snr.
• FUNCTION: connect_to_emu_without_snr.
• FUNCTION: enum_emu_snr.
• Device "NRF52832_XXAA" selected.
• FUNCTION: read_device_version.
• FUNCTION: read_device_version.
• JLinkARM.dll CORESIGHT_WriteAPDPReg returned error -1.
• JLinkARM.dll CORESIGHT_WriteAPDPReg returned error -102.
• FUNCTION: close_dll. FUNCTION: close_dll.

When I run nRFgo Studio, I get the following message, and when trying to recover:

My nRFgo Studio is version 1.21.2.10.

I've been able to put the device in bootloader mode, and reload the J-Link OB bootloader image, but this did not make any difference. Another post suggested disabling mass-storage device mode, which I have done through JLink Commander, but still no luck.

Does anyone know what may be wrong with my device?

[mjw]

Fair enough. :) The board is unmodified and the components look intact. Luckily I have another NRF 52840 PDK, and with the same PC, tool versions, and USB cable, that one is recognized correctly, so I'm suspecting faulty board or firmware. The problematic board is recognized by J-Link Configurator and it has the same J-Link OB firmware as the working PDK (SAMU128-V2-NordicSem V1.00).