When connecting the charger only the orange status light should be turned on. If both the orange and the green lights are on when the charger is connected something is wrong.
Check that the battery connectors are firmly attached
Check that there is no dirt or corrosion on the robot charging connector, spray with 5-56 or WD-40. To keep the charging connector in good condition, always rinse the connector after automatic washing.
Check the cables between charging connector, battery and junction box for damages