While I have no idea if there was fraud, it has been reported in major media that there were substantial discrepancies (between actual votes and tallied votes) in some of the ballot boxes that the PRD was able to get opened. If the tribunal takes this or anything else the commies present seriously, one of two things seems likely to happen: A Gore-style cherry picking operation in which commie precincts are recounted until they produce more votes, or a nationwide manual recount, which I doubt can happen in Mexico without chaos that would make Florida look like a tea party.
I read a bit about this in the Mexican press yesterday, and it appeared that the PRD was claiming that some votes were not legible, the markings were blurred, etc. In other words, it seems to me that they actually managed to get some disqualified or are claiming that they should be disqualified, going for a version of the old "hanging chad" technique that served the Dems so well.