i'm not too familiar with how the under hood main fuse box is in relation to the battery, but i have fixed a few new[er] vehicles wiring problems by looking for the "green death" in the wiring bundle or under/by the battery tray.
it seems the battery gasses over time, degrade the insulation and connections close by the battery, causing all kinds of goofy stuff to happen.
look close at all the ground connections [if any] by the battery as well. they may look good on the top side, but hide "green death" under them, and possibly creeping up the wire as well, under the insulation.
just something else to look at.
hopefully, it will be a relatively easy fix.