Hi everyone, I realize pre-made bikes are frowned upon, I came accross a Sondors Rockstar 150 for a great price, but no battery. The batteries are 850.00 so that is a no go. Its 48v 21ah battery, which i found one online, made an adapter cable for the existing harness and conneted it. I suppose I am a bit nieve to think that would have "just" worked.

The bike has the bafang 750 ultra mid drive, thats the extent of what i knw about it. The battery connector has a very thin blue and yellow wire next to the negative prongs of a 5 pin connector, then a space the the positive. The original battery has an on/off switch that you turn on prior to hitting the power button on the handlebars. So I connected my battery, and I get nothing, button on handlebars has no effect. Does anyone know what the two small wires on the connector are for, is there some signal that needs to be there? Any help would be greatly appreciated.