Try the headlights and/or the horn. They are on different circuits, not off the ignition switch. If they work, that almost eliminates the battery connections.
Then try the heater, which does come thru the Ignition switch.
If it blows, this points to the NSS, so like said, try neutral, and with the key in crank-position, just wiggle the shifter lever a lil. If it cranks, re-align your shift mechanism.
If it won't crank for nothing, but the heater blows, then you will need to prove the starter relay is functioning.
HOWEVER,
In your case Having also died while moving, the first thing I would check is the bulkhead connector, and/or the Fusible link. Well, actually first the Fusible-link, then the connector. That big fat wire has a tendency to develop a high-resistance, which then makes heat, which then melts the plastic all around it, and finally the the connector just stops passing juice. I think it's either Red or Black, or maybe red going in and black coming out; I forget, but it's the only FAT wire in there, 10 gauge I thnk.
If the Fusible link has blown, yur gonna have to figure out why, before you replace it with another, like-sized link, else it will just blow again. If the headlights were on when it blew, check that circuit. If the headlights were off but you were stepping on the brakes, check that circuit. It should have blown the fuse, but sometimes water gets into the back of the fuse-box, and then, anything can happen.
