After short circuiting the output and applying a voltage exceeding 7V on the input (solar panel) the charger does not switch from 12 to 24 V. I followed the steps in the manual, but is does not work. The fault message reads charger or PV over-voltage. The charger has never been connected to a computer or Color control panel. What can be done to change it from 12 to 24 volt as the system was working on 12V before.