Alright, the idea and intent was good, but it suffers from a lot of problems.
First thing is that the rhythm is all messed up. You start out with a gallop, then due to the rhythmic problems is becomes a reverse gallop. Your melody adds an extra beat somewhere in there.
The production is the second thing that catches my ear. The mixing is terrible, at the moment. The melody is drown in the rhythm and drums. Bring the melody up and the rhythm down (I think the drums are alright). Listen to some common thrash or death metal music (Megadeth, Arch Enemy, Death, etc.) - Listen to how they deal with leads and solos. The melodic parts stick out above the rest of the music.
The pitch is very off in many places (namely whenever the second part of the source is involved). Study the source better and figure out what's going on.
In it's current state it's hard to make out what you wanted this to sound like (thus I can't comment too much on the structure of the piece). This needs some serious cleaning up.
I will add, though, that this particular song could make for a great metal mix if done properly, and I commend your effort (actually playing an instrument for a remix deserves respect). The effort, however, is very messy. Clean it up, fix it up and put it back up here and we'll get into more of the details.