<VV> Need advice - battery hooked up backwards; what damage likely took place?

[Kinzelman, Andy]

Guys,
A club member bought a new battery - and mistakenly hooked it up reverse polarity.  He said it was obviously wrong (sparking like mad) - I don't think he got to the point of trying to start it yet.  After correcting the error he has lights, horn, etc. but the starter won't engage.
My guess is he likely damaged the alternator and/or regulator - anybody know?
What about the starter - if he didn't try engaging it I doubt he damaged it - again looking for expert advice.
Anything else likely damaged?
Thanks,
Andy K
Wisconsin