Just to share my similar experience. I found a Vado 4.0 SL EQ at a shop about an hour away. That particular model/color was so hard to find, I slapped down my $500 deposit and drove out to get it the next day. At the shop, I took it for a test drive and noticed a couple wonky things:
1. The motor would just jump levels without any input from me. Went from 0 to 2 suddenly.
2. On attempting to change levels, the motor wouldn't respond.
Back at the shop, explained what I was seeing. They took it for a test themselves and started doing some diagnostics. An hour later and no answers. They said they would have to reach out to Specialized and it would maybe take a week. Ugh. Could you have possibly tested it before I drove an hour out there??
Anyways, only a few days later they advised that all was well. They said they talked to Specialized, and they sent a replacement for a couple of the parts. They had to swap out the head control unit (where you turn it on/off) and the wires that connect it to the motor. I drove back out, took it out for another spin, and all working as designed. (I do notice when you turn the motor on, it takes a couple seconds for the display to show up and stay lit after the initial battery indicator flashes on and off...I'm not sure if this is just normal behavior).
The shop advised that Specialized said this was pretty rare, but who knows. I'm also skeptical whether Specialized was in fact involved...I think they may have just swapped out the head unit with another Vado they had, as when I setup the bike in Mission Control, it displays as a different color bike (again, not sure if this is normal).
In any event, I desperately wanted the bike, and ETAs at other local shops were at least 6 months out, so I decided to roll the dice for what it was and take this one that they fixed the head unit on. So far so good.