Check the voltage at your battery. It should be above 12V. If it is, then look for a breaker inline for the 12V loads. If you have less than 12V yu may have a blown fuse at the converter. If your battery voltage is below 12V then you are probably going to need a new battery. Oh, did you ever check the water level in your battery? It could have boiled dry and shorted the battery causing a fuse to blow at the coverter too.