A couple of mornings ago, my 2010 Prius experienced a battery drain and would not start. It was completely dead. After figuring out that I could get the battery out, I did and charged it to 12.5 V. Once reinstalled, the dash lights came on brightly but the car would not start. (The smart key has a new battery in it.) I was also unable to turn the dash lights off when I tried. Ultimately the dash went dark. I could hear a humming noise after everything was supposedly off and the battery had drained down to 9V when I tested it after another removal. Has anyone here had a similar issue? What needs to be done? I have a code reader. Can I read error codes with the 12V battery out of car?