AM1+ (3 months old, 1000 km on clock)
Just had a rubbish morning where I got no electrical response (display wouldn't 'boot up;' no response from throttle thing) from a fully charged battery and having had no issues yesterday on return from work. After some investigation when I got home today, I discovered the issue. I've just let Analog Motion technical team know and I'll post my explanation to them below. Hope it helps you if you have a similar issue.
When I got home today, I was able to do a bit more investigation and discovered that the wire connection that joins up within the lower tube of the frame had disconnected. I just happened to give it a tug from the handlebar end and it felt a bit loose so braved pulling it fully out of the frame and then reconnected it out with the frame to test. That got the connection live again and after a little bit of head scratching, I managed to work out how to feed the wires back through the frame.