The error code 06 means that battery has discharged below the acceptable voltage threshold. The cause could be that the scooter has been idle for too long and discharged below the threshold or that the Undervoltage threshold has been set too low. You can find the correct Undervoltage setting for your scooter in the setup manual.
In order to change the configuration, you can cycle through the settings by just pressing the power button once turned on.
You will see the letter V (looks more like a U) where the mileage is usually displayed. This is the voltage.
Also, ensure that P03 and P15 is correctly set.
Another possibility is that the charger is defective. Do you have a voltmeter at home? If you do, please measure the charger output - it should show 54.6V+