I am also experiencing this exact same issue. and have seen similar postings with others  Makes me wonder if there are a bad batch of controllers.

I commute daily for 3 seasons and my bike just sat in my living room for the past few months. I have two Rad bikes. The RadCity 5+ with this issue and an older RadCity 3 which I also still ride and never an issue.

After turning the bike on and no error codes all cables plugged in and no battery problems the throttle and pas failed to move the motor. I am working on how to fix this issue just now.

Hello..
I purchased a RadCity 5+ from a second party which was not under warranty and which also has a bad battery that would not take a charge. After some investigating I discovered that it was a blown fuse located inside the battery pack and fixed it after watching a few YouTube videos.

Another day, afterwards I blew that fuse at the end of a very long ride where I was tired and accidently touched the battery lock key to the bike charge input instead of the keyhole. After a large spark the battery no longer worked and i knew what the problem was and how to fix it

Now I'm even more careful when even plugging in the charger and first plug in the bike to the transformer and then put the power cable that's already in the wall into the charger transformer itself. Never had an issue since.