Hi, and welcome to the forum.
1. I'm not convinced that it's an Enertia Plus as all the E+s I've seen say "Enertia+" on that aluminum frame. Like this:
The craigslist one just says "Electric," which is what my 2010 Enertia classic says. The Enertia plus has twice the range of the Enertia classic.
2. Missing the charging cord isn't a big deal, as you can order those directly from Brammo.
3. I see a bottom body panel that isn't attached in that photo, but it looks kind of beat up...might just be shadows on it. It is missing the side panels though, and I'd think that you'd want all the panels on it to protect it from the weather.
4. Screen doesn't light up. Does he mean that the display doesn't work, or just that the backlight doesn't work? If the screen doesn't work at all, you'd almost have to get a replacement from Brammo and I have no idea how much it would cost. Otherwise, you'd have no way of knowing the state of charge of the battery - how much range you have left.
His declaration that the main battery has a charge on it... well, there's no way of knowing how much of a charge is on it without being able to see the information on the display screen.
Caveat emptor my friend. That said, if it really was in decent shape - as in, the battery had been cared for over its life, they are a hell of a lot of fun.