Q: nRF52840 DK does not appear as a removable drive named "JLINK"

[ramsringar]

Q: nRF52840 DK does not appear as a removable drive named "JLINK" 
Steps I followed
1-Connected the NFC antenna to the board.
2-Used a micro USB 2.0 Data cable(Fully functional and tested) to connect the nRF52840 DK to one of your PC's USB port.
3-LED 1 has started pulsating
4-buttons SW1 to SW4 LEDs are pulsating.
5-No removable drive named "JLINK" appeared on my computer(windows 10)
6-Tried BOOTLOADER mode....nothing appeared on my computer(windows 10)
7-NFC enabled phone prompt to open a URL near NFC antenna. (Success)
8-Tried with two more USB data cables.(to appear "JLINK")...Nothing happened
9-Tried with 2 more windows 10 computers..no result
10-Trying to resolve the issue since 9-10 days. Please help!

[haakonsh]

My first guess is a faulty J-link driver. 

I suggest you use the following CMD command: nrfjprog -f nrf52 -e

This will find any jlink thats connected to a nrf52 device and do an erase all operation on the connected nrf52. 

My second guess is incorrect settings of the various switches on the DK. What are the states of your switches? And what is the voltage of VDD?

[ramsringar]

Tried nrfjprog -f nrf52 -e command....and -r reset....LED blinking stopped.

then msdenable from jlink commander...no result
Programmed new hex file...Led started blinking
But JLINK drive not appearing on my computer.
Tried jlink driver version: JLink_V640, JLink_V640b, JLink_V642

Please help!

[haakonsh]

What was the output from nrfjprog? It sounds like the jlink driver does find the j-link OB device on the USB bus. 

[ramsringar]

Commans: nrfjprog -f nrf52 -e

Output: Erasing user available code and UICR flash areas. Applying system reset.

Commaqnd: nrfjprog -f nrf52 -r
Output: Applying system reset.
Run.

Command: nrfjprog -f nrf52 --program led_softblink_pca10056.hex --chiperase --verify

Output: Parsing hex file.
Erasing user available code and UICR flash areas.
Applying system reset.
Checking that the area to write is not protected.
Programming device.
Verifying programming.
Verified OK.

[haakonsh]

I don't understand, this is the expected behavior of the DK. It's working just fine.