First of all I’m assuming the Argon m2 board and the SSD are matching. Because there are two versions of the board, m2.sata or m2.nvme.
I have the Argon V2 m2.sata too and this is the m2.sata drive that I run in my V2 board: Fikwot FN203 512GB M.2 SATA SSD - SLC Cache 3D NAND TLC SATA III 6Gb/s M.2 2280 NGFF Internal Solid State Drive, Up to 550MB/s, Compatible with Ultrabooks, Tablet Computers and Mini PCS : Amazon.co.uk: Computers & Accessories
Assuming you have an m2.sata drive the Argon m2.sata board “accepts any size of M.2 SATA SSD with B-Key or B+M Key”. As you can see in the amazon link my SSD has a b+m key.
The Argon v2 board has a ‘b key’ socket. So only a b-key or b+m key will actually fit correctly.
You might be able to wedge an m key or b+m key drive in the wrong way around - but god only knows what happens if you try that. You may have already destroyed the drive or the board or both, who knows, lets hope not
Anyway, b key or b+m key is the correct one and the b side has 6 pins and must be on the left.
There may be different lengths but thats about it.
Slot it in and fasten the screw.
After that boot up the thing from SD card, login or ssh into it and check the available drives. You can use several commands for that depending on what OS you boot from the SD card. The commands may require ‘sudo’.
‘lsblk’
‘fdisk -l’
‘parted -l’
The SD card will be something like /dev/mmblk*something and the SSD will be most likely /dev/sda.
You can do whatever you like with it from there.
In my particular case on the SD card I booted from I had also copied a recently downloaded libreelec image. Which I simply wrote to /dev/sda with the ‘dd’ command. Then I powered down, removed the SD card and the next boot was libreelec from SSD.
Hope this helps