Our co-op doesn't work on the e-part of e-bikes for the simple reason that there is an appalling absence of standardization in the electric parts of these bikes. There is a near-limitless range of incompatible differences in battery configurations, connections, shapes, and sizes (think of all the differences in battery-powered power tools and then multiply that). Plus controllers that only talk to specific proprietary boards, at least three different standard voltages, and you start to understand why the person abandoned the bike when it stopped running.