Another joke from Shimano:
It says that: "It has been confirmed that there are cases where the bicycle cannot be started after the BT-E8016 battery has been fully charged. If this occurs, plug the charger into the battery, confirm the LED lights up, then remove the charging plug. This enables the bicycle to be started. Rest assured that this issue has no negative effects on safety. We will inform you as soon as a permanent solution becomes available. "
So if you have this issue while riding your bike in the mountains and far from home, you only need to carry a charger and find a wall outlet wherever you are riding and you can easily fix the issue and carry on.
It says that: "It has been confirmed that there are cases where the bicycle cannot be started after the BT-E8016 battery has been fully charged. If this occurs, plug the charger into the battery, confirm the LED lights up, then remove the charging plug. This enables the bicycle to be started. Rest assured that this issue has no negative effects on safety. We will inform you as soon as a permanent solution becomes available. "
So if you have this issue while riding your bike in the mountains and far from home, you only need to carry a charger and find a wall outlet wherever you are riding and you can easily fix the issue and carry on.