MES control panel on a 2008 Autosleeper Nuevo

Hi, I hope you don't mind me asking another question this evening. We have just purchased the 2008 Nuevo and after a lot of research found we were able to set it up on site without problems. But, we have concerns about the built in battery charger on the MES control panel, I'm doing the right process according to the hand book and followed it to the letter...... I have checked all fuses I can find and still no joy, I have also used a multimeter to guage leisure battery which was low at maybe just under 12 volts. The problem is it will charge from the vehicle alternator but not the MES control panel.
One thing I'm thinking is should I here a slight umming noise coming from the panel, if so I cannot. Any advice please.
TIA

You will only hear the hum of the charger cooling fan when it is charging at a high rate, ie when the chosen battery's voltage is low. The first thing is to check if the red light on the switch is lit. This is hard to see because of the location of the charger. Alternatively on the MES screen select 'hab' and then on the detail screen check its voltage. If it is charging it will read the voltage output of the charger, typically 14v.