Hello, I have an ebike that I wanted to get more range out of it. So I installed a new front motor (1500w 48v) on my fat tire 750w 48v rear fat tire ebike. It all seemed to work before I installed. But when I installed and tried hooking up that battery the display screen will not light up. I checked all of the connections and it seems ok. I read that the sparks are a natural occurrence when connecting the battery. As a novice I'm stumped. Any help would be appreciated. Thank you ahead of time.