Can't program nRF52840-MDK using nRF Connect ver 3.11.0, Programmer ver 3.0.0

[Nik-Scan]

This is the first time I'm trying to use this dongle. I followed all Nordic instructions on how to install everything and at some point it told me to insert and program the dongle. First I didn't press the RST button, the Programmer recognized nRF5284 (F1498C5AB09C), but it displayed a message "Error when fetching device version: readFwInfo error" and all "Device" buttons in the menu were disabled.
Then I tried to hold the RST button while attaching the dongle to USB, but the LED would blink red once or twice and after that it would turn green. I don't know why, but once the LED stayed in this blinking red mode, but when that happened the Programmer didn't even recognize the dongle.
Any idea what to try next?
Thank you.

[Nik-Scan]

I just read the issue #61 that explains more about this problem. It turns out that my board shows in the windows explorer as "MDS-DONGLE" with 3 files on it: current.uf2, index.htm and info_uf2.txt. I just want to ask if the current.uf2 is the bootloader file and if it needs to be removed once another uf2 is copied to the dongle.
Thank you