nRF52840 preview development kit booting error

[Elissa]

Hi, I'm writing this because of nRF52840 booting error

I got this product today and It worked well, but after I downloaded one of the example's ~DEBUG.jlink file to the kit, I could not reach to the kit via PC anymore

The jlink file was "proximity example file" and my phone still can detect the nRF52840 kit and connect to it (and works very well)

HOWEVER, the PC could not reach to the board and so that could not download or use other programs

Could anyone help me??? I tried 

https://devzone.nordicsemi.com/f/nordic-q-a/24592/my-nrf52-nrf51-dk-kit-doesn-t-work

and 

https://devzone.nordicsemi.com/f/nordic-q-a/25794/nrf52840---not-detected-on-win10-pc---anymore/101583#101583

but any of them works for my case

Thank you

ej Park.

[Edvin]

Hello,

If you are still able to detect the nRF with nRF Connect, it suggests that it is the programming chip that is corrupted. You say that you have tried the steps in the links. What happens when you hold the button "IF BOOT/RESET" while you power off and on the PDK? Does it appear as BOOTLOADER on your PC?

If it does, can you try to drag'n'drop the attached file into the BOOTLOADER device (e.g. in windows explorer).

After this, the "LED5" next to the programming chip should start to blink. When it does, power the board on and off, without holding any buttons. Does it appear on your PC then?

If this does not work, where in the process does your board differ from the description above?

You do use the USB port on the short side of the DK, and not the long side?

J-Link OB-SAM3U128-V2-NordicSemi 170724.bin

Best regards,

Edvin

[Elissa]

It does not work, unfortunately. It does not appear as BOOTLOADER on my PC....

[Edvin]

What positions are the switches on the board in? is SW9: VDD,    SW8: ON,    SW6: DEFAULT,    SW10: OFF,    and SW7 Def. ?

What version of JLink do you have? If it is an old one, could you try to update to one of the latest releases? And also, is it possible to test the PDK on another computer?