What would it take to confirm or refute the Snowball Earth Hypothesis? Since Harland's sedimentary work and Budyko's models in the 1960s, geologists have hypothesized that the Earth may once have been completely frozen. There are various lines of evidence for this event.

What would it take to conclusively confirm or refute this hypothesis, short of going back in a time machine?
In order to confirm the snowball earth hypothesis, we'd need at least:


A paleogeographic model which extends to greater than 650ma and has been shown be be conclusively accurate throughout that entire period. (i.e. one we can trust)
Sedimentation structures/patterns (or other paleoclimate proxy data), consistent with a glaciation event, tied into the same time period, from the north pole to the south pole