I have been arguing that your #1 scenario applies but don’t see how you get the 538-0 vote. Why would Obama votes go to McCain? Why would they not just be disqualified?
You gotta remember - there are 1076 possible electors (counting only DEM and GOP).
Obama’s current count is something like 350-188 for McCain.
If Obama were DQ’d, his electors would also be DQ’d and replaced with McCain’s 350.
350 new McCain + 188 original McCain = 538.
Assuming they all vote McCain, then 538-0.