When the display goes blank, it means there's no power from the battery.
The most likely problem is a connection, becuase it happened at a stop, not when you restarted.
It could be any connection between battery inside the pack, to connector between pack and cradle, to wires between cradle and controller, to the plug between controller and display.
It could also be the pack's BMS has shutdown to prevent damage to the pack, from a cell that's too low. That sort of shutdown would be more likely to happen when starting back up from a stop, though.
Does the battery have a little LED meter on it's case to show charge level? If so, does it display anything when you push the check-button on the meter?
If not, the problem is likely inside the battery.