Could use some advice not starting

streetyme

Hello put my wifes 2009 370Z in storage the first of December. Car ran absolutely fine before, went up once every couple of weeks to start it up and check it out. We went to pick it last night battery was dead.. I used a jumper box to try and get it started paying close attention to Negative and Posative cables.. Hooked it up and the lights started flashing and horn was going off.. After that shows a little car on the dash flasing with a key in it.. Its like its not reconizing the keys.. Oh and where the push button start is normaly would light the ring around the button now when I depress it just show the words Lock Do I need to change battery and if so is there any special procedures that needs to be followed? Any advice woould be so welcomed

Thanks