We plugged into the grid at a caravan park to boost the battery charge (as we have done many times) and within an hour it tripped the campsite fuse at the mains. Upon switching it back it will no longer charge the battery via grid. Invertor working fine and inverting using car batteries. Lead is working do not an issue here. It won't tick over to charge mode. Any help appreciated to allow us to top up the batteries again with mains power.