I got the new E8020-charger finally (5th replacement) and new batteries from Shimano by warranty, and the new E8020 seem to work perfectly in colder temps, too. So far so good.
Searched for similar problems, and came across this thread. I have returned no less than 4(!) chargers through my dealer, and now also 2 batteries, due to the issues with charging and failure codes. The parts are currently at Shimano for yet another replacement. Sits on a 2018 Scott e-genius...