Bad news, and more bad news. After removing the panel I still can't find the relay box. So, I instead used a few test leads and a 12 volt battery to test the actual fans themselves. Upon tapping the leads to the fan terminals the passenger fan spun right up. Driver's side, nothing. Let's also not forget the melted solder that ended up on my bumper right above the fan.

Looks like a new fan is in order at the very least. After that, I'll need to figure out what caused this.