Would like to know why the band has been blacklisted? Searched on the forum but could not find.

They released a single yesterday, pretty metal, and an album is coming through Napalm Records as probably is well known.

Yeah, about that. I brought up the mentioned "single" to the mods and it was determined to be more of a preview than a legitimate single. So to appeal the band, you'll have to wait till the album comes out. I also asked them to blacklist the "International" instance (since they refer to themselves as Brazilian/Dutch band) as well, just so that no one tries to circumvent the blacklist.

Well, I hope I'm not mini-moding, but, as far as I know, their single isn't a valid release, because it is only about 4:30 minutes long (even though it is refered as 5:11 IIRC) and it doesn't haves an unique cover art.

Blacklisted because multiple people thought it was a great idea to submit them based on a preview track from an upcoming album (you call it single).
Standalone singles need to have their own, distinct cover art and not just the cover art of the album they belong to.