Majorian's fleet is not burned. He invades Vandal Africa and defeats them. Now, much depends on what sort of resistance they offer. The Vandals were pretty convinced they were doomed if he managed to invade, so I don't know what they do to challenge him. Now, Majorian will look great, the WRE gets a new lease on life, yadda yadda.
How might the ultimate settlement look with the Vandals down in Africa? I could envision allowing some remnant as federates, while Rome controls the citites. But would this be secure enough for the grain supply, or might Majorian try to utterly wipe them out?