Are you 100% sure there is only the one fuse box?
Not the same problem, but i ripped a dash out assiming the bulbs had blown,
only to find that there were 2 fuse boxes??
1 under the bonnet, and one under the passenger well. (Different make of car).
Replaced the fuse and they worked
If the wires had fused, i'm sure other things on the loop would also behave strange?
Anything else gone pop, or not working now?
Hope this helps??