Dead 12 Volt Battery Problem

I haven't posted in a long time--learned so much when my Prii was new (Nov 2009) I haven't been back. Move this please if in wrong place. I left my car door open last night, car in garage. Dead battery today. We have a spare 12 volt battery--replaced the original this year but kept it for emergency use for my husband's CPAP machine in power outages. It went dead at about 45K miles when he sat and listened to the radio for an hour or so and we were told it needed replacing. He charged it and it held 12.3 volts since the charge in April 2017. He was going to replace the dead battery with this old one but can't get the back hatch open. You also can't get the car out of park with the battery dead to push it out of the garage next to the truck to jump start it. He jump started the car in the garage with the 2nd battery and drove it for awhile and left it outside. Thankfully we had that extra battery that still worked. I have to use the car tomorrow morning to go the 14 miles into town so hopefully with have some juice back it when I get home. Is there any way to get around getting the car into neutral when the battery is dead--and get the hatch up?