nRF52840 Not Detected by nrfjprog / Recover Fails - Need Expert Advice

Question

Hello, 
 I'm having a serious issue with my nRF52840 board. Here’s what I already tried: 
 
 What I have done:

Verified working USB cables (data + power).

Installed SEGGER J-Link drivers.

Installed nRF Command Line Tools (latest).

nrfjprog --help works fine.

Installed Zephyr SDK and built a simple hello_world project.

Tried west flash and nrfjprog --recover .

Installed J-Link Configurator (no device shows up).

Tried multiple USB ports and cables.

Tried flashing with Arduino IDE — still no COM port.

Windows sees the device only as "USB Device" (driver missing). now it wont see it at all

Current problem:

nrfjprog --recover gives: ERROR: No debuggers were discovered.

No COM port appears.

No J-Link detected.

Board only makes a USB connection sound when plugging in (sometimes). now not at all

Thanks for your help! I would like to try everything possible before giving up.