same thing happen to me still not working this is still a mysterious issue thats been happening to alot of the sn-100 not sure if its the motor or controller , hull sensor ? if your in the USA contact Vtuvia USA First if they don’t resolve it than Contact Vtuvia Manufacture direct in China send a email tell them whats wrong all info they will help you.
Question did bike get wet before this happened ?
Q: do you have a 3 pin connection or 9 pin Connection Wire going from the hub motor to controller ? you will see it may have to cut a zip tie just unplug that wire look at both ends let me know / Clean it if wet or dirty and reconnect it
go to this link
its for a ebike but just tap number 23 and 24 read follow the troubleshooting checking wires and connections hope that helps if not just send a email off to Vtuvia good luck hope its resolved soon and let us know exactly what it was a $7 part sensor or wire or a controller or motor issue.