I recently purchased an nRF52DK from mouser (the sticker says PCA10040 3.0.0 2023.4)
I installed nRF Connect for Desktop v4.2.1 on my Windows 10 PC (during the J-Link installation I selected the option to install the USB driver for J-Link).
I connected the device to my PC and powered it on (the LED5 lamp is flashing quickly and the LED1 lamp is pulsing slowly).
No Nordic, J-Link, com ports, or anything new appears in device manager when connecting the device (I'm not exactly sure what to expect, but I assume some sort of J-Link related device).
I launched the Programmer tool, and nothing appears when I click "Select Device".
For troubleshooting, I tried:
Rebooting.
Another USB cable.
Another Windows 10 PC.
Reinstalled nRF Connect for Desktop.
Launched JLink.exe and I get an dialog box saying "No probes connected via USB" (I'm not actually sure if this is supposed to work, but I thought it was worth a try).