I mean, let's not overthink this.
Why not a physical key to turn where the button is now?
Or how about a small hole straight through somewhere, basically just big enough to accommodate a kryptonite-style lock through the board?
I had a surge this morning that sent me backwards onto the asphalt when my Pint went full-speed ahead. I was riding on my new Hoosier wet-weather treaded tire, just logging some kms to get used to it, so I had my upper body pads on, in addition to the wrist guards and helmet that I always have. Lucky thing – tore my coat on the elbow, but the pads did their job. Hopped up and rode another 6km* in a mild state of shock. lol.
I was at 38% battery, and I never felt any surge like that on the stock tire on that much battery (2400 km on that one). OTOH, this new tire is very soft and very energy inefficient compared to the stock slick tire. May well be that I won't be able to ride it like the old tire due to the additional drag all the time. I'm 85 kilos and run with it at around 22 psi, so far.
Headwind; soft tire, cold temperatures, low battery – it all seems to play into the possibility for drama in the form of surges/nosedives.
*Note: Yep. Range extender, but I've got 1000 km riding with that, too, and it's never been an issue.
There's a 30km forest trail on the island where I live in Sweden, and it just serves up one surprise after another. Sometimes it's a great sunset, like in the picture. Other times, as you're silently floating over pine needles, you can experience nature -- like the time I rode alongside 5 deer that were running through the forest by the trail. Or that time my buddy just about got t-boned by a buck that was crossing the trail at a full run. OK, never floated with wolves. That was clickbait, but I have floated with a curious red fox!
Anyway, there's no other vehicle that's so quiet, so smooth and so well tolerated by the other people on the trail than my Pint. 13 out of 10 will float again and again.