Ok, I took a look at the board with a small mirror. I still can't see the battery, but I can feel it with my finger (it sure is the barrel type). What is not funny, is that I can see a corrosion mark (complete with rust on the edges) where a small puddle seems to have been on the "floor" of the tower... right beneath the battery.
I still have hope, because the mobo is in vertical position, it probably didn't do much damage... well, I guess I'll have to dissasemble it.
Where on earth will I find a replacement for the battery? Does the Amiga work without it?