Ok, so here's my findings....
I pop in a new 20a fuse into position "O" below (red star), and all interior lights come on and stay on. However, in the process, I removed the red power input connector in the slot highlighted with the red circle. Due to it's shape, I had to pop it out to get the new 20a fuse in properly.
Once I inserted the connector back into the slot, I noticed that I have no power to my amps and no power seats. The end of the connector is rusty so I assume I need to clean it off and re-insert it.
The manual doesn't have any info, but what exactly is powered via that slot highlighted with the red circle?
So in the process of fixing one item, I come out of it with no power seats, no amps and worst of all, my rad started leaking. :x