Hmm, if it's just four digits, you might be able to guess your way in... I haven't seen ebike systems that lock users out. Often times 1111, 1234, 1818 types of things will work. If you start with 1 and then cycle the remaining three digits... then start with 2 and cycle the remaining three digits etc. you might eventually get in. This is not legal advice, just something I've done when trying to figure out ebike settings myself