I have a working code using SoftDevice 140 7.2.0 and Segger ES on the nRF52840 DK. I made the single adjustment of the preprocessor variable BOARD_PCA10056 to BOARD_PCA10059 as indicated by the tutorial. I used the nRFConnectProgrammer to flash the dongle. I must admit it is very confusing as when one follows the instructions one gets all kinds of error messages in the log which looks like it failed. If you don't do anything after pressing the reset and doing the flash write, the dongle appears dead. THe log says to hit the reset so I do. Then the red led flashes again. Not what I expected. In any case, if I pull the dongle and re-insert it, there is no LED lit at all. The dongle looks dead. However, it turns out that it is working.
Previously I had a version of SoftDevice and the pc-ble-driver installed on the dongle, and when I plugged it in the green LED lit. With my program flashed on the dongle, there is no green LED even though it is working (it is sending advertisements). That is bad for the user. Why is that? What did I NOT do? I expected the green LED to light when the program was flashed as with the pc-ble-driver. Alas, not so.