Quick fix: KTE-LCD-3 electric bike controller

Introduction Yesterday my neighbour came in asking to take a look at his electric folding bike. It had been beaten up during transport in his van and the controller on the steering wheel no longer responded to the power button. He had taken it to two different bike mechanics, but both of them weren’t interested. The brand was unknown to them (and likely to just about everyone) and, most often, they don’t really care much for electronics in general. Figuring out which modules to replace (much less actually attempting to repair them) most often is not within the scope of what they do. It didn’t help that he had no idea where the bike was originally purchased (it was inherited from some family member long ago), or how old it was. An electrician at his job had measured voltage up to the controller and “everything was working as it should”.