The fan update

I think I have figured out why my ceiling fan and front ceiling light stopped working along with the bath light and fan.  A blown fuse.  Duh.  Unfortunately, replacing it causes the replacement to blow immediately.  With the DC power on, I got a spark when putting in a new fuse.  Now, how do I find out why?  Do I have to dismantle everything to find a short?  What a drag.  Guess I'll be disconnecting the batteries and following the wire.  When I bought the van, the inverter, converter were blown due to a short in a wire under the fridge.  I wonder if mice have been busy?   At least I have a decent chance of getting it fixed now that I have a reason for the problems.