Electric Sleigh

Was shopping a used 2017 C-Max Energi ~40,000mi. Saw what must have been a bit of corrosion under the carpeting in the trunk. Wasn't able to actually see the battery since it needs some tools to open up. Does this look like something that would be a problem? My older hybrid never had anything like this. I can't get an image to attach for some reason, but here is a picture.

My '13 SEL push start will unlock the doors and honk if it detects the key inside. Locking again at that point overrides the safety feature.

Another user in the keyless entry part of the forum stated a FOB was $80. Seems cheap, wonder if they're right. Edit: To clarify, I think they mean the intelligent key for a hybrid SEL.

Going to revive this from the dead. Isn't 2 stage unlocking just when pressing the FOB keys, not unlocking by pulling the handle with FOB in pocket? New owner, and I'm still wrapping my head around someone being able to open my car just cause I'm standing nearby. I highly doubt this will ever result in problems, just weird.