Not clear from your wording (honestly due to lack of punctuation), but sounds like it sat for a year without being plugged in. And when you plugged it in your 12 volt stuff was not working. There are some devices that always draw 12 volt power and will drain a battery over time if not connected to shore power. Likely your battery was drained completely.
Did the 12 volt stuff work after you pulled the charger back off? Or only while you had the charger on? You may just have a bad battery that will not hold a charge. I would pull the battery and take it in and have it checked.