What can you cook if you hook the battery up backwards when boosting?

[davepl]

I gave a friend a jump-start today and on the dead vehicle he hooked the cables up backwards. Fortunately it was completely dead, which is probably better, but there was still some sizzling, but no smoke. Sat that way maybe 4-5 seconds I'd say. I generally prefer people to hook up their own end but that didn't pan out today!

The key was OFF at the time in the problem vehicle.

Afterwards, once connected properly, the car wouldn't start because the electric fuel pump wouldn't run, so that's a sign something went wrong somewhere. Gauges, lights, everything seems to work except the fuel pump.

My car, which was running at the time, appears ok (at first the ALT light was on but there's a wiring issue because it was actually due to the parking brake being on), everything seems to work.

What would have cooked on the car being boosted that was hooked up backwards? Would you roast a fusible link, or would it not cause damage at all?

Thanks
Dave