I have a 2006 Scion xA. I've never jump started a car before, so when my sister asked me to start hers, I googled it. The instructions said to start with both cars off, so when I tried to start hers, I forgot to turn mine on first. So, obviously, I couldn't get hers started, but the surprise was a half hour later it was time for me to go to work, but then mine wouldn't start either. I'm pretty sure my battery is fine, because the radio and lights work fine, but when I try to start it, instead of cranking it just starts clicking. I also have check engine lights on (which have been on for the past month) and a friend checked the codes and said that I probably needed a new gas cap to remedy the evap codes and a new crankshaft position sensor for another code, but it's been fine until I tried to start her car today.