94 540 no electrical power

My 540 has no electrical power. I tryed junping it, I've got it on a charger right now, but nothing happens with key in the ignition, when I open the doors the lights donot come on. Is there a master fuse or relay Ineed help?

Are you sure your charger is Charging???? Most battery chargers these days have 'polarity protection' circuits. IF the battery is 'FLAT' [very low state of charge/voltage] this circuit won't allow the charger to function......i.e., very dead battery, no charge unless it's got an 'override' setting.