It happens quite frequently when the battery is completely empty that the balance of the hoverboard goes out of order.
Just do a fairly simple procedure, the RESET:
– Put the hoverboard in parallel position on the ground, hoverboard in position OFF (important)
– Then press for 30-40 seconds the “turn on” button
– Release the button a few seconds
– Push last time to turn it off
Wait a few seconds and turn it on again. Everything should be back in order
You can watch on Google or YouTube, there are plenty of videos, just search for “Reset Hoverboard”