Rev limited, no reverse on an '03?

[Copper]

I just got an '03 600HO with electric start and DESS. It had been sitting for 3 years, so the battery was long since dead and full of rotten fuel. I drained it and put in a new battery, and it fired right up, but has a problem - it revs to 3000ish and holds with a miss, and the beeper chirps continuously. The book says it's a DESS connection issue, but I'm not sure, since it starts fine and idles.... is there anything else that can cause that? The reverse doesn't work, either, probably related?
Wondering if there was anything else to check before I haul it to the dealer (2hrs. away).

 

[cubby]

Wiggle the dess plug or take it off and look for corrsion. Being a 03 does it even have reverse? Does it have the gray button right below the hand warmers?

 

[Copper]

The plug looked okay, but I cleaned it up with contact cleaner, then brasso, and still nothing - squeezed the contacts some, wiggled and twisted and everything, still nothing. There's an "x"-shaped tin plate inside the cap, what holds that in? I wonder if it's corroded underneath it....

I was told it has reverse, and it talks about it in the manual - it's a 007 edition, might have been included in the package?