Hi, same issue with the battery here, first started by cutting off while downhilling, maybe once or twice per ride, it was annoying and confusing, but didn't payed much attention, I guessed it was just a bug, and probably would get sorted with upcoming updates, but it just got worse, and I started to hear some rattling noises then it just wouldn't switch on anymore, I was 1/4 up a pretty long climb, luckily it was cloudy, because it's mostly shadeless, as i had to push the bike up, or else I had to pedal for at least 12km to get home, instead of 7 or 8 km, which most of it is downhill, other than the 2km up pushing the bike on a gravel road, when I got home, I've investigated a bit and found the tabs broken as many here, I brought the bike to my friend's shop, which happens to be a bosch authorised service dealer, and diagnose revealed most likely to be a failed connection of the battery, we where at the phone with bosch tech support to guide us and to diagnose further to discard any other possible problems, we could confirm as most of the times the diagnostic tool would not pick up the battery, motor and connect module, wich in most cases means the battery is not connected, even though the battery was lached carefully, just discusing the issues we concluded that it would be more reliable if the connection to the battery was at the bottom end of the battery, with a plug connector instead of a fixed socket to the frame, as the battery will be pushing down with its weight and the movement of the battery wont affect the connection as it would be flexible, because a 5kg battery will move, specially going downhill on rough terrain, a similar setup as the spec levos.
The most annoying thing is that almost 2 weeks went by and the bike has been packed and ready to be picked up for almost week and a half, I'm going on holidays for the month of August and the bike was part of the holidays, bummer, hopefully this gets fixed for good, because if they only replace the lach mechanism, the same issue will come back, for sure.
Just wanted to mention that I've only taken the battery out a couple of times, when new and another time to show it to some friends, as I don't need to remove it for charge.
Cheers