My nRF52840 was recently corrupted. I was able to run through reset and downloaded the latest MCU 'J-Link OB-SAM3U128-V2-NordicSemi 170724.bin' onto the board. So now it shows up in bootloader mode when connected to my PC. However, under Device Manager, it showed up under USB controller, but not under Ports (COM & LPT). The J-link was broken.
I have tried the following things to fix J-link. None of them worked.
1. Used a different cable;
2. Connected to a different USB port;
3. Uninstalled device under Device Manager and reset the board;
4. Disabled the device and updated the device driver;
5. Drag-and-dropped an application hex onto the board during bootloader mode. The board remained in bootloader and didn't go to app;
6. reinstalled 'J-Link OB-SAM3U128-V2-NordicSemi 170724.bin';
7. Tried nrfjprog -- recover. The error message was 'no debug device connected'.
Please help. Thanks in advance.