controller diagnoses

Hello. I bought a gift for my girlfriend's son, a used Leader Fox arimo bicycle. In the Netherlands recently, I thought that in the first place the seller is honest, in the second that even if there will be any problems I will find a workshop and eliminate the breakdown. But I was wrong, no one...

Hi, I'm a handy person who is in search for practical knowledge on a couple of intriguing things: The first and for most item is a controller from ebikeling 48v 35a 1500watt. I am most interested in and wishing to learn is about the board itself what the noted points are for? How can I test...