I have had many phone calls over the years asking why Scooters stop pulling away without fiddling with the key. Especially in shopping centres.
Mobility Scooters in general, especially the better brands like Shoprider, have a built in battery saver programme in the Control Unit. It senses when the key is on but there has not been any driving for a few minutes. Normally the driver is chatting to a friend or in a shop.
To save battery power it switches the Scooter off.
Just turn the key off and back on and all is reset and ready to drive again.
P.S. Check your tyre pressures!