> No way, the heat output is way too high for a Di2 battery pack, and this idea also does not explain why the thermal signature would only occur during certain phases of the race.
I concur, but it's important to rule out other possible explanations. For example I've had two Di2 batteries fail, in one case the gears worked intermittently and when I removed the battery it had swollen up. I guess it's possible my battery produced heat spikes before finally giving up the ghost but i'm not a battery expert so am only guessing!
I'm not trying to defend anyone but just want to point out there may be other equally plausible explanations.