2014 Focus only starts when jumped

My girlfriend left her focus sit for a few months and now it only starts when
jumped. Yesterday we drove it around for half an hour and then let it idle in
the drive way for another 15 minutes, as soon as I turned it off it failed to
come back on. It makes no noises, or sounds of any kind, and none of the
electronics work at all. No dome lights when the door opens, no dash gauges,
nothing. I thought the issue might be because we weren't letting it run so the
alternator wasn't able to charge the battery, but after 45 minutes of work
yesterday I don't think that is the issue.
The battery terminals look good and clean, I haven't looked inside the cable
coverings though. I'm very unfamiliar with this car so I'm not sure what other
issues to look for.

Thanks!