Interesting Im suspecting the same problem. My almost new Rad 5 turns off right after I turn it on and I hear a faint click from inside the controller.  I've reconnected all the connectors.  RadPower is sending a replacement.  I'll examine the old one. I suspect something in there is shorted.  I'll put a plastic bag around the new one. 

I just removed my old controller and it is air tight, filled with foam to keep moisture out.  Just saying.   Moisture didn't get it.  I'll install replacement when it arrives.

Tried to start Radrover 5 today, after winter.  Last rides were October.  Bike is only a year old.   The screen flashes on then off.  It won't stay on.  I also hear a slight click in the controller as if a circuit breaker let go.  I've followed the website instructions and un-assembled all the connectors, checked them and replugged them back together.  But something is causing the controller to turn off within a second after I turn it on.  Any ideas?  I am discussing with Rad support and we'll let you know.  I did carry it on back of our motorhome so it got rained on.  My wife's Rad Stepthru is fine, under the same circumstances. Might the controller have a short?  Or might something else be shorted?   I've also tried disconnecting the lights and motor and turning it on, but same result.  The screen comes on the click off.  The screen seems to be fine.  The battery is fully charged.  I tried a second battery same result.  Is there a reset sequence for the controller?  If so what?  Thanks for your ideas on the problem.