Watch out as this probably is Mellanox made but not branded (don't be fooled by Mellanox signage).
Probably this is a switch with EMC (?) firmware.
Mellanox made and branded 6000 series are black and violet, this is black with just white text which probably means that I'm right.
Been there already myself, made the mistake
although with help of a forum member we were able to turn the switch into unmanaged one. However I was told that it's not a straight forward process.