Something isn't right. Fuse "b" should only be a 16A:
20A for a window fuse? That's too high. Use only the red or white (forgot which is which but they're 8A or 16A only). The next one is a blue 25A. Not sure why you have a 20A fuse there.
Do you have the fuse diagram on the fuse box cover? This should list the fuse rating and color you need for the specific application.
What happens if you remove the aftermarket wire going to the fuse box? Does this still lead to a blown fuse "b"? Use the correct 16A fuse!
