best way to troubleshoot a light

First post here!!!! Here's the deal I was replacing an indoor light (12V) in a 2000 Ford E350 panel van. When I was tinning the wires I shorted the + and - with the soldering tip by mistake. There was a little spark then no voltage. I assume I blew the fuse, but the thing is this van has been modified and the fuse box is at the back panel and really hard to get to. After checking all the fuses they all seem good. What's another way to troubleshoot this? I tried to trace the cable but I lose it after a few feet as it's hidden in the panel's wall at the back.

Did you check the fuses with a meter or just visually?Kevin Pierson

Just a visual check on the fuses!!! The thing is I don't know which one is which in the fusebox. Everything seems to be fine in the van. I checked other things that are wired to the same battery just to make sure and everything works fine. I wish I could fine the other end of that cable, I could send tone on it. There's a row of some sort of tabs on the wall   they look like some sort of junction tabs. Where does each ends go to? And how would I re-wire the whole thing if I have to?

How can I wire a new cable to that light from a battery with a fuse as well??

It's a domelight I was actually thinking of just jumping that new light from the already existing domelight. but the thing is that the domelight only turns on when the doors are open. I need that new light to be on it's own. I have an auxilarry battery at the back which is not wired to the chassis battery.