Suppose you had a scooter sit idle for a couple years. You didn't charge the batteries terribly often, and one of the batteries starts growing one of those poofs of white powder. You open up the scooter and find a bit of the powder at the bottom of the battery compartment. Additionally there's some rust and peeling paint.
That's what has happened with my EVT 4000. The amount of this white powder isn't very much.
I'm assuming the powder is some sort of acid?
(BTW the rusted parts I know how to handle - get a grinder, grind the rust away, then paint with rustoleum)