Battery hooked up wrong

If you're lucky, just the battery.

If you're just a little unlucky, the Fusible Links, generally mounted in the fuse block under the hood.

If you're totally screwed, they took out the voltage regulator, which is usually attached to the alternator. There are replacement regulators available.

Unfortunately, you didn't say what year/model, so these are generalizations...

You are very lucky that the battery did not burst.

Check the 100 Amp main fuses in the engine compartment and the fusible links.

Right. If it's a newer model (with a computer) he could well have lost it. If the smoking was from wiring rather than the battery, at minimum he's looking at replacing the wiring harness or parts of it.

I especially like the "someone" and "they". Heh.

Usually it is a "friend".

That did the trick for me when I hit the wrong terminals with my jumper cables, quick and cheap fix. I don't know if kooking up the battery wrong is worse though.

Actually on older Toyota's it is easy since colors reversed from most American cars. Been there and done that with no damage on an 83. On an 87 a friend took out a fusible link.