My device ID is the following:
It doesn’t go at the line 52. It goes at the line 48 and gets stuck in test_run_info((unsigned char *)"DEV ID OK");:
Regarding the hardware modification, yes, I did it. 
Ok, so for this particular example this is a normal behavior and it’s showing that your hardware is working quite good. Here the software will write DEV_ID OK and then go on an infinite while loop.
If you open a terminal, then you can see that message showing.
That’s good news!
I couldn’t see anything on the Terminal, though… What should I do/run on the Terminal to be able to read the message?
On the other hand, I tried to build the project for the nRF52840 and I’m told that “boards.h” is missing? Is there a documentation for the nRF board and the API that I missed?
You should open serial port with a Terminal (Tera Term for example) then when you reset the board you’ll see the message.
For nRF52840DK, I think you’re missing the SDK.
You can find infos in the note below already inside the package
Yeah, I opened a serial port with PowerShell and set the speed/baud rate to 115200 (I also tried 9600 just in case), but I didn’t get anything. 
I’m guessing it should have worked too with PowerShell?
Anyway, I’ve tried it on TeraTerm just to make sure but I don’t see anything still…
Regarding the nRF52840DK, I’ve just followed the tutorial and downloaded the SDK and still no luck. 
