TOXICMAN: tl;dr
1. An error with the Mission Elapsed Timer (MET), which incorrectly polled time from the Atlas V booster nearly 11 hours prior to launch.
2. A software issue within the Service Module (SM) Disposal Sequence, which incorrectly translated the SM disposal sequence into the SM Integrated Propulsion Controller (IPC).
3. An Intermittent Space-to-Ground (S/G) forward link issue, which impeded the Flight Control team’s ability to command and control the vehicle.