I'm not sure if this is exactly the same problem, but yesterday morning I couldn't start my Evo Big Bud Pro (have had it for 3 months). I knew the battery was 100% charged (the green led lights on the battery confirmed that as well), but the display continued to show 0% and the 0% was flashing rapidly. After numerous attempts to remove and mount the battery again, checking the cables and the contacts, reset the display, etc. etc., nothing seemed to solve the problem. I realized that I had to ride the bike unpowered all 7k to my ferry and then another 3k to the Evo store.. However, after only like 7 minutes on the bike cursing loudly the display suddenly showed 100% battery and the motors kicked in. Puh! When the store opened at 10 am I called them and explained the issue and they told me to bring it in after lunch.
At the store the service guy informed me that some of the early 2016 bikes had some kind of problem with the battery (don't ask me the details) due to a bad construction/production choice, and that the store had received information about how to fix it. It took about 45min to fix and it looks like he took the battery apart and at least glued a bit since I could notice some glue around the contact. They also adjusted something so that the battery is easier to remove and put back in, and also the key for the battery is easier to turn now. Hopefully the fix will do the trick so I won't be standing there in the morning with a "dead" bike knowing that it will be an absolute nightmare to commute to work.
As I said, I'm not sure if this is the same issue as you are experiencing, but I guess that it could happen during a ride as well.