Newer releases of the UF2 bootloader are found at the top of the page. Find the .ino file with your board's name and with the newest version number. The file will have the following naming scheme (with [your board's name] replaced by the name of your board and vx.x.x-adafruit.x replaced by the newest release number):update-bootloader-[your board's name]-vx.x.x-adafruit.x.inoFor example, if you wanted to download the UF2 installer for the Arduino MKRZero, you would look for a filename like update-bootloader-mkrzero-vx.x.x-adafruit.x.ino. Click on that name to download the .ino file.
Upload UF2 with ArduinoIn Arduino, click on File > Open..., and locate your downloaded .ino file. Select it, and click Open. If you get a pop-up window stating that the file "needs to be inside a sketch folder" with the same name, click OK.
What programmer can I use? I found one on amazon, that has a 10 pin connector, which is what the board that I have has (cortex debugger/programmer pins-per the official RobotDyn site). You said that I can use another SAMD board to program it again? I have a few more of the same exact board (9 to be specific), but I can purchase a programmer if you could suggest one for me.
I have this one https://www.embeddedartists.com/products/lpc-link2/before it I used https://learn.adafruit.com/programming-an-m0-using-an-arduino/overview# once. with luck@pert has more info to this topic